HOYLAKE, England -- After American Brian Harman hit his opening tee shot of the final round of the 151st Open Championship at Royal Liverpool Golf Club on Sunday, someone in the grandstands shouted, "Hit it in the bunkers!"

When Harman, who came into the round with a 5-stroke lead, pushed his approach shot right of the second green, there was an audible cheer from the gallery.

After Harman grabbed a 5-stroke lead with a 5-under 67 in the second round Friday, it seemed like all of Great Britain wanted anyone to win but him. He had turned England's Super Bowl into a first-half rout and never relinquished the lead.

Harman, the 26th-ranked player in the world, finished his surprising run at rain-drenched Royal Liverpool by carding a 1-under 70 in the final round Sunday to win the Claret Jug with a 72-hole total of 271, which was 6 shots better than South Korea's Tom Kim, Austria's Sepp Straka, Australia's Jason Day and Spain's Jon Rahm.

Harman's 6-stroke margin of victory matches the second largest in Open Championship history. Only Tiger Woods won a Claret Jug by a wider margin: 8 at St. Andrews in Scotland in 2000.

Harman, 36, is the oldest first-time major champion since Spain's Sergio Garcia, 37, won the Masters in 2017. He collects $3 million for the win.

Harman, a 125-1 underdog to win The Open, wasn't a favorite in Las Vegas or outside the ropes at Royal Liverpool. He probably wouldn't have wanted it any other way.

On Saturday, while playing with Englishman Tommy Fleetwood, Harman said he heard some things that were "unrepeatable."

"I'd be lying if I didn't hear some things that weren't super nice today toward me," Harman said. "I hear them, but at the same time, I don't try to let that influence the decision I'm about to make."

On Sunday, fans cheered loudly for Fleetwood, who grew up 30 miles away in Southport, England. They tried to rally Rory McIlroy, who won the last Open Championship at Royal Liverpool in 2014 and was trying to end a nine-year drought without a major championship title.

They cheered for American Cameron Young, the long hitter who started the final round closest to Harman at 5 shots back. They pulled for Rahm, Straka, Day and Kim, who was playing on a badly sprained ankle, and anyone else who seemed capable of turning a three-day blowout into a thrilling ending.

They just didn't pull for Harman, at least not until it was too late to cheer for anyone else. That moment came on the par-4 14th hole when Harman drained a 40-foot putt for a birdie. He made an 8-footer for birdie on the par-5 15th to move to 13 under.

"I think it's good for Harman," said PGA Tour player Harris English, who was one of his teammates at Georgia. "It kind of puts a fire in him. He knows he's not a favorite. I think it gives him satisfaction to show everybody that he's one of the best players in the world."

There's little doubt about that now after Harman joined Bob Charles (1963) and Phil Mickelson (2013) as the only left-handed players to win a Claret Jug. It is his third PGA Tour victory and his first since he won the 2017 Wells Fargo Championship, which was six years and 77 days ago. It was the fourth-longest winless drought in PGA Tour history to be snapped by a player's first major championship victory, according to research by ESPN Stats & Information.

With the victory, Harman is expected to move to No. 3 in the Ryder Cup points. The top six players in the standings after the BMW Championship on Aug. 20 will be automatic qualifiers for the American team that will compete against Europe at Marco Simone Golf and Country Club outside Rome on Sept. 29-Oct. 1. Harman seems all but assured of making the team for the first time.

"He's a mudder, he's a grinder," U.S. team captain Zach Johnson said Sunday. "For lack of a better cliché, he's a bulldog. I think he's made for this, you know? I've played a lot of golf with him and been around him in and out of the ropes for quite a while now. What I've witnessed the last three days, absolutely none of it surprises me at all. No shock. No surprise."

As one of the smallest players on the PGA Tour at 5 feet, 7 inches and 150 pounds, Harman has been overlooked and underrated throughout his entire professional career. It's the reason he has played with a pot bunker-sized chip on his shoulder for so long.

"People underestimated him on the baseball field and football field, everywhere," said Patton Kizzire, one of Harman's closest friends on tour. "As a golfer, you can make up for it. You don't have to be the biggest one. I think he loves being the underdog."

After carding just one bogey in the first 36 holes, Harman found early trouble for the second straight round Sunday. On the par-4 second, he hit his approach shot past the hole. He chipped to 20 feet and needed two putts to make a bogey. He made a 7 ½-foot putt to save par after missing the green on No. 3.

He found trouble again on the par-5 fifth hole, after pushing his tee shot into thick gorse down the right side. He had to take a drop, and his third shot was well short of the green. He failed to get up and down and made a bogey 6 to drop to 10 under. Suddenly, his lead over Rahm was down to 3. Fleetwood and Straka were 4 strokes back.

But then, just like Harman did after two early bogeys in the third round, he settled down. He hit his tee shot on the par-3 sixth to 13½ feet and sank a birdie. On the par-4 seventh, he drained a 23½-footer for another birdie to get back to 12 under. His lead was once again 5 strokes over Rahm and Straka.

After carding five straight pars, Harman made another bogey on the par-3 13th when he missed a 7-foot par putt, his first miss inside 10 feet in the entire tournament.