THE TORONTO RAPTORS needed a bucket. Time to target James Harden, right?

Down six points against the Houston Rockets in the closing minutes of a Dec. 5 game at Scotiabank Arena, the Raptors cleared out on the left side of the court and tossed the ball to their go-to guy, Pascal Siakam. He caught the pass a couple of steps above the block and went to work, a skilled 6-foot-9 scorer eager to exploit Harden with his 4-inch height advantage.

Siakam faced up and took one left-handed dribble before turning his back to the basket again. But Harden didn't budge.

Siakam pounded his dribble once, twice, three times with his right hand. It was an old-school, Charles Barkley-esque approach, but Siakam was the one getting bullied.

Harden muscled him farther and farther away from the hoop.

After Siakam finally picked up his dribble just inside the elbow, back still to the basket, he pivoted as though he was going to shoot a turnaround over his right shoulder. Harden forced an awkward air ball when Siakam attempted that shot on a post-up in the third quarter, and Siakam was hoping to create some space by getting him to bite on the fake this time. Harden wasn't fooled.

With Harden still within whiskers' distance, Siakam settled for a tightly contested jump hook from just inside the free throw line that never had hope of going in. The ball clanked off the front of the rim, too low to even have a chance at a lucky bounce.

"We switch so much that they've got to target somebody," Harden recently told ESPN. "I play so many minutes that they feel like they can just exploit me. I mean, it hasn't worked."

Giannis Antetokounmpo eagerly reminded people of Harden's defensive reputation after the All-Star Game, blurting out after his team's come-from-ahead loss that their strategy during the fourth quarter was "just trying to find whoever James Harden was guarding."

Harden has been a defensive punch line for the majority of his career, a label attached to him years ago in large part because of moments of embarrassing indifference. The reality: Harden holds up remarkably well when opposing offenses target him in isolations, which happens more often than with any other player in the league.

He's one big reason the Rockets have gotten away with exclusively playing small ball, daring offenses to choose one of two paths: Try to push them around or go small themselves and play right into Houston's hand.

During a 9-3 February that included double-digit wins over the Los Angeles Lakers, Boston Celtics and Utah Jazz, the 6-foot-7-and-less Rockets remarkably generated a top-seven defense. Even if they regress closer to league average on that end, this small but powerful defensive unit might be enough to sustain a contender with a relentless offensive machine.

"You can't try to play matchup basketball," a Western Conference head coach said. "That's what they want. You have to beat them with [ball] movement."

Harden hopes teams take Antetokounmpo's advice and make picking on him the focal point of their game plan.

"Come try it," Harden said, "and the s--- won't work."

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THE BIG QUESTION in Houston: Can the Rockets survive defensively playing so small?

It seems that opponents ought to be able to beat up on Houston with a simple game plan. Just dump the ball to your big guys on the block and let them be bullies.

The problem, as Celtics coach Brad Stevens put it: "It's hard to post linebackers."

That starts with P.J. Tucker. He's officially the shortest starting center the NBA has seen in ages, packing 245 pounds and a ton of attitude on his 6-foot-5 frame. Like a middle linebacker, he's also the loudest voice on the defense, as Tucker's baritone is constantly barking instructions, communication that is critical in a switch-everything scheme.

Whether Tucker actually plays center in the Rockets' defense depends on the matchup. It's more accurate to refer to Tucker as the Rockets' defensive stopper, as he typically takes the toughest frontcourt assignment. The Rockets coveted Robert Covington -- coughing up a first-round pick in addition to center Clint Capela to get him -- because they considered him a perfect fit for the style they planned to play, a forward who spaces the floor as a 3-point threat and is capable of defending multiple positions.

The 6-foot-7, 211-pound Covington is more volleyball player than linebacker, a term that Golden State coach Steve Kerr has also used to describe the Rockets. With a 7-foot-1 wingspan and 36-inch vertical leap, Covington is the closest thing to a rim protector in the Rockets' rotation, having averaged 2.5 blocks in his 10 games with Houston, almost all coming as a help defender.

"Teams think they have a mismatch by going inside, and they don't." An Eastern Conference scout, on Houston's small-ball defense

Two of the Rockets' top guards -- 6-foot-3, 215-pound Eric Gordon and 6-foot-5, 220-pound Harden -- are both comfortable banging against taller foes who want to catch the ball on the block.

"It's kind of a unique team in that our little guys can guard big guys," Houston coach Mike D'Antoni said, citing a significant factor in the Rockets' decision to commit to small ball, a style that has unleashed Russell Westbrook to wreak havoc with the floor wide open because of shooting threats surrounding him.

Opponents might be able to shoot over Tucker, Gordon or Harden, but it usually won't be from the spot they want, and they won't elevate with great balance as the shot is released.

"Teams think they have a mismatch by going inside," a scout from an Eastern Conference team said, "and they don't."

That's especially true with Harden, who often starts games with the opposing center as his primary defensive assignment, allowing Tucker to defend the most dangerous frontcourt scoring threat. According to NBA Advanced Stats, Harden has defended a league-high 101 post-ups this season, allowing only 0.60 points per possession on 29.5% shooting. That's tied for the stingiest of the 50 players who have defended the most post-ups.

This isn't a statistical fluke.

Harden allowed 0.68 points per possession on a league-leading 212 post-ups defended last season. That tied for second stingiest among the 50 highest-volume post defenders, behind only Gordon (0.55). His numbers were similarly impressive the season before.

"He's strong as hell and smart as s---," a rival Western Conference assistant coach said of Harden.

The Rockets essentially invite teams to pound the ball inside by playing small and switching every screen. Pick-and-rolls, the bread and butter of the modern NBA offense, tend to break down into post-ups or isolation plays.

After Boston's second loss of the month to Houston, Stevens explained why the Celtics were so reliant on isolation play. He credited Houston's defensive execution, saying the switches forced Boston away from the rim while the Rockets thwarted slipping screeners.

"Their physical presence is real," Stevens said.

If the hope is to keep up with Houston, then come up with something smarter than trying to exploit Harden. Although he isn't dominant as an isolation defender, Harden is by no means an easy mark. He has the second-most isolations defended in the league this season (98) and has allowed 0.82 points per possession, ranking in the 61st percentile. He allowed similar marks the past two seasons.

In other words, it's a bad idea to put a bull's-eye on Harden unless you have one of the league's few elite isolation scorers.

"I'm a competitor. I'm a beast," Harden said. "Whatever teams' schemes are, we switch everything, and they've got to find a way to attack us. It's not going to be perfect. Some guys are going to score on me. That's a part of the game, but more times than not, we're going to get a stop and they'll shy away from it."

PLENTY OF SKEPTICS remain after the Rockets' month-plus sample size of small-ball success. "I think they really undervalued Capela," one NBA general manager said.

One theme pops out from the Rockets' three losses since they dealt Capela: Houston was dominated in the rebounding department, losing the battle on the boards by an average margin of 21 in losses to the Phoenix Suns, Utah Jazz and New York Knicks.

The letdown factor likely played a role in the losses to the Suns (the night after beating the Lakers, with Westbrook resting because of the back-to-back) and Knicks (two nights after a win in Boston). The Rockets' leaders were critical of their effort and intensity on those two occasions. There's an understanding that attention to detail in rebounding must be a major emphasis for Houston to succeed with this style.

"You have to box out hard," D'Antoni said. "Before, we didn't box out. Now, you better box out, so it's got their attention."

The other weakness created by not playing a center -- Tyson Chandler guarding the inbounds pass when Utah's Bojan Bogdanovic hit a buzzer-beater is the only possession logged by a traditional big man for the Rockets since the trade -- is a lack of rim protection.

This was the primary concern cited by the skeptical general manager, and it was an issue the Jazz exploited to fuel a comeback in the game they won in Houston, when guards Jordan Clarkson and Mike Conley were able to comfortably finish after beating their primary defender off the dribble. The West assistant coach who heaped praise on Harden's post defense mentioned that the best way to attack him when he's guarding a center was to force him to be a help defender near the rim.

"There are going to be holes," D'Antoni said. "It's not going to be like it's going to be an easy win. They're going to exploit things if we can't stay in front of our guys. Now it becomes, can you guard the guy in front of you?

"But it's them, too. And we happen to think we have the best two one-on-one players in the league. Where's their rim protection when we're shooting 3s out there? If we can play our style the right way, then they've got to make a choice also."

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HOUSTON'S MOST RECENT trip to Staples Center on Feb. 6 wasn't just another regular-season game. D'Antoni called it "a big test" of the Rockets' all-small approach.

There was no turning back, not after the trade deadline passed hours earlier. The Rockets were being mocked on NBA Twitter for their plan to try to slay the West's giants without a traditional big man in their rotation. Tucker found humor in the criticism, posting on Instagram a picture someone photoshopped to put him on stilts while he was standing in a defensive position.

In the caption, sandwiched by a bunch of laughing emojis, Tucker wrote: "the internet is 1000000000000000000 and 0 yo."

Houston was 10-1 in games Capela missed thanks to injury, so the Rockets had reason to be confident entering the meeting with a Lakers squad that featured a frontcourt standing 7-foot, 6-foot-10 and 6-foot-9, the latter two perennial All-NBA talents in Anthony Davis and LeBron James.

The Rockets' bet is that they can make their foes blink first, playing opposing big men off the floor by exploiting their vulnerabilities defending in space. The Lakers indeed blinked, as big men JaVale McGee and Dwight Howard combined to play only 20 minutes in L.A.'s loss. The centers' only playing time in the fourth quarter came in garbage time.

Harden started that game guarding the 7-foot, 270-pound McGee. He finished it defending either Danny Green or Alex Caruso and came up with a couple of critical defensive plays during the Rockets' 9-0 run that iced the win.

When LeBron James attempted a lob from half court to Caruso -- a pass that would have led highlight shows and subjected Harden to ridicule if completed -- Harden read the play and tipped the ball away before recovering it and hitting Westbrook with an outlet pass.

A couple of possessions later, Harden was in help position as James drove down the lane, with Covington staying in front of him, and delivered a kick-out pass to Green in the corner. Harden closed out quickly enough to keep Green from shooting off the catch and mirrored his steps when the Lakers guard drove to his left. After a spin move, Green attempted an off-balance floater that Harden contested. Harden grabbed the rebound, pushed the ball in transition and got the hockey assist on a dagger 3 by Covington.

"A lot of this is having a firm belief in it, players believing in it and then imposing our will," D'Antoni said several days later.

"Then our strengths become what wins. But if they impose their will -- if they outrebound us and knock us around and we don't root 'em off and all that, if we don't guard at all -- yeah, then it's crazy and we won't win."

ESPN's Tim Bontemps contributed to this story.