BOSTON — Aroldis Chapman said he never lost confidence, even as he struggled.

“Not at all,” he said through his translator Sunday after turning in his second straight good outing, earning his ninth save in the Yankees’ 3-0 victory over the Red Sox in Game 1 of a split doubleheader at Fenway Park. “I’ve had bad days, like anybody else in baseball, but my confidence is up high and I’m ready to pitch again.”

Joe Girardi made it clear that wouldn’t be Sunday night, or Monday night in Minneapolis, either. Chapman pitched for the third straight day Sunday afternoon.

“There was [hesitation],” Girardi said. “We talked to him a couple different times. He kept reassuring us he was OK. He can reassure me [Monday], but he won’t pitch.”

Chapman didn’t record an out Friday night in blowing the save and taking the loss, allowing two ninth-inning runs, two infield hits, two walks (one intentional) and a misplayed grounder as the Red Sox beat the Yankees, 5-4. He rebounded with a scoreless 14th in the Yankees’ 4-1, 16-inning victory Saturday, then struck out a batter and allowed a two-out single Sunday in a 21-pitch ninth. Fifteen of those pitches were strikes.

“There wasn’t a lot of healthy swings off him that may have been happening in the past,” Austin Romine said. “There was a lot of feeble swings and some ground balls.”

For a second straight game, Chapman, who threw all fastballs Friday night, mixed in his slider and changeup.

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“The other day I had a conversation with Romine about maybe using the slider a little more,” he said. “Today we did that. It was good today.”

Clippard improvement?

Tyler Clippard, whom Girardi demoted Friday, made it two straight scoreless outings in Game 1. He pitched the eighth Saturday and the seventh Sunday, relieving the starting pitcher — Luis Severino and CC Sabathia — each time.

Extra bases

Game 1 represented the Yankees’ second shutout of the Red Sox at Fenway this season, the first time since 2002 they accomplished that . . . Aaron Judge had an infield single in five at-bats in Game 1 and extended his on-base streak to 42 straight starts, the longest streak in the big leagues this season.