LOS ANGELES -- The Los Angeles Dodgers played one of their sloppiest defensive games of the season and watched it end on a robbed home run by Chicago Cubs center fielder Pete Crow-Armstrong. But Tuesday night provided them with an unmistakable dose of optimism -- Yoshinobu Yamamoto returned after a three-month hiatus, and his stuff looked as sharp as ever.

Before the Dodgers lost 6-3, dropping their division lead to 4 games, Yamamoto limited the Cubs to only a run in four innings of work, during which he struck out eight batters. His fastball averaged more than 96 mph. His splitter and curveball looked devastating. His command was as sharp as anyone could have reasonably expected, considering he hadn't pitched in a major league game since suffering a strained rotator cuff June 15.

"It was pretty surprising," Dodgers catcher Austin Barnes said. "I didn't know how he was gonna look coming back from this, and he looked better than ever."

The Dodgers have been ravaged by injuries to their rotation throughout the season and entered Wednesday with only one lock, Jack Flaherty, to start games for them in October.

But then Tyler Glasnow, out since Aug. 11 with what the team has described as elbow tendinitis, threw his second bullpen session, prompting trainers to clear him for a two- to three-inning simulated game Friday.

And then Yamamoto looked a lot like the player the Dodgers imagined when they awarded him a 12-year, $325 million contract this offseason, the largest ever for a starting pitcher.

"I feel much better about the rotation tonight than I did 24 hours ago," Dodgers manager Dave Roberts said. "It's starting to turn in terms of getting back to the rotation that we had envisioned."

Yamamoto began his outing with three consecutive strikeouts -- of Ian Happ swinging at a curveball in the dirt, of Dansby Swanson swinging through a splitter that darted just below the strike zone and of countryman Seiya Suzuki looking at a full-count fastball that painted the outer edge of the plate.

The Cubs tacked on a run in a second inning after ground balls were mishandled by shortstop Miguel Rojas and first baseman Freddie Freeman. But Yamamoto struck out the side again when the Cubs' lineup turned over in the top of the third and ended his outing by getting former Dodgers prospect Michael Busch to ground into an inning-ending double play in the fourth.

Yamamoto, speaking through an interpreter, said, "Today's outing turned out much better than I expected."

He threw 59 pitches and should be stretched to about 75 pitches when he takes his turn Monday, with three starts left to prepare for the postseason.

"We'll take this every start going forward -- fastball command, both sides of the plate, hits the low dart, the split down below that, stealing a strike with the breaking ball," Roberts said. "It was really good."