CHICAGO -- Michael Kopech was in a self-admitted rut.

Despite a scoreless outing featuring two strikeouts in Friday’s victory over Boston, the White Sox reliever had allowed 17 runs in his last 13 1/3 innings pitched with his ERA jumping from 1.52 to 3.95 in 13 games. Those struggles disappeared during a 9-8 Red Sox victory in 10 innings Saturday night before 37,854 fans making up the 14th sellout of the year at Guaranteed Rate Field.

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Kopech hurled 2 1/3 innings, striking out five, walking one and seeming to overmatch a potent Boston lineup during his time on the mound. His stellar outing, with a fastball topping out at 100.2 mph and averaging 98.1 mph, per Statcast, helped facilitate a White Sox comeback from a 7-2 deficit after three innings.

Among his seven whiffs recorded, per Statcast, Kopech got four out of his 24 four-seamers thrown and three out of his seven sliders. He finished off three strikeouts with the fastball and two with the slider.

“Yeah, the one from last night, I felt pretty good, too,” Kopech said. “But I didn’t just execute some pitches. Tonight, I was able to go out there and have the same amount of aggressiveness and attack hitters, but I was able to execute some of my secondary stuff a little bit better and it played well.”

“Kopey, the more he throws, the better he gets, especially when he's out there on back-to-back outings or he's throwing multiple innings,” said White Sox catcher Yasmani Grandal, who played in his 1,000th career game Saturday. “The more he gets to throw the ball, the better feel he gets, and we can go from there. But the ball was definitely jumping today."

Saturday’s loss might have been a little frustrating after the White Sox battled back from a 7-2 deficit in the third by scoring five unearned runs in the fourth. That rally was punctuated by a three-run double from Luis Robert, who matched a career high with four hits and set a career high with three doubles.

Boston scored seven runs in the third off starter Dylan Cease, who recorded his 200th strikeout of the season by fanning the side in the first. But he also walked five and threw just 40 of his 71 pitches for strikes in 2 2/3 innings.

“Honestly, I chalk tonight up to just one of those, I don't want to say outlier games, but one of those games that just happens every once in a while,” Cease said. “It's one of those where it's not going to make me lose any confidence.

“I already have a good idea of what I feel like I need to work on. I'm going to hit my next four days hard and get ready for the next one."

Grandal delivered the go-ahead run with a solo shot in the fifth, also producing his fifth career season with at least 20 home runs. The Red Sox (81-63) tied the game at 8 in the eighth with a run off Craig Kimbrel and won it in the 10th with a run off Mike Wright Jr.

Although the White Sox (81-61) had first and third with nobody out in the bottom of the 10th, southpaw Josh Taylor struck out Leury García and pinch-hitter Danny Mendick and got help with a great defensive play from second baseman Enrique Hernández and first baseman Bobby Dalbec on Brian Goodwin’s ground ball to end the game. Andrew Vaughn was unable to pinch-hit, per manager Tony La Russa, due to achy legs.

“It’s hard for him to swing and he can’t run,” La Russa said. “It was a great effort on our part. Heartbreaking, very tough to lose.”

“Overall, it was a great game,” Grandal said. “It just so happened we ended up on the losing side. But a lot of times, these types of games are the ones that teach you the most, especially when you come up as a loser."

Cleveland being no-hit by Milwaukee’s Corbin Burnes and Josh Hader dropped the White Sox magic number to clinch the American League Central to 11. But the Kopech outing became the most crucial moment of Saturday.

“It was more self-inflicted than anything. I don’t think my stuff is necessarily bad,” said Kopech of his rut. “It was just kind of getting in my own way. Trying to do too much. And I think, sometimes, a little bit of bad luck.

“That happens in baseball. You can’t really control that. But I feel like I was able to take two steps forward today and that’s a good sign.”