NEW YORK — Drew Pomeranz needed 91 pitches to get through five innings against the Yankees on Saturday afternoon. The lefthander had allowed only one run to that point, but the day had been a struggle for him.

“The whole game I wasn’t as sharp as I’d like to be,’’ Pomeranz said.

The Red Sox, thanks to the wonder of expanded rosters, had 11 relievers available in their bullpen, pitchers of all shapes, sizes, and talents.

But Pomeranz came back out for the sixth inning in a tie game.

Manager John Farrell believed Pomeranz had enough for three more outs. The starter certainly had earned the right to try, given his strong performance over the course of the season.

Three batters later, Matt Holliday hit a home run deep into the left-field stands and the Yankees were on their way to a 5-1 victory.

The Sox managed only six hits against Masahiro Tanaka and two relievers; so one in-game decision did not decide the game. But on a day when Pomeranz was fighting to command his pitches, pushing him for one more inning was a mistake.

The Red Sox, trailing 1-0, tied the game against Tanaka in the sixth inning. Eduardo Nunez doubled, took third on a ground out, and scored on a wild pitch.

Pomeranz to that point had put seven runners on base but stranded six of them in what had been a strenuous outing.

He also was approaching the end of his rope. Pomeranz averaged 98 pitches in his previous 26 starts, 91 in three games against the Yankees.

“Felt he was still in good shape,’’ Farrell said. “Talked with him after the fifth, after he came out, still felt good.’’

Leadoff hitter Didi Gregorius drew a walk, but Pomeranz stayed in to face Chase Headley, who had homered in the second inning and singled in the fourth.

Despite the two previous hits, Farrell wanted Pomeranz to face the switch-hitter. The alternative, having Headley bat lefthanded and take aim at the short porch in right field, was not attractive.

“We’re trying to keep Headley in the bigger part of the ballpark,’’ the manager said.

Headley lined a single into center. With Brandon Workman up in the bullpen, Pomeranz stayed in to face the righthanded-hitting Holliday.

That clearly was one batter too many. Pomeranz’s first pitch was a 92-mile-per-hour fastball over the plate and Holliday crushed it.

Pomeranz was trying to jam Holliday and missed his spot. It was Holliday’s first home run since July 15 and first hit since coming off the disabled list on Friday.

“I had beat him in there a few times. I think it was a pretty good pitch but I think it was what he was looking for and he put the right swing on it,’’ Pomeranz­ said.

Pomeranz (14-5) suffered his first loss since June 11. He allowed four runs on eight hits with two walks and five strikeouts.

Seeing the Yankees for a fourth time wasn’t much a factor, Pomeranz said.

“It obviously changes things a little bit,’’ he said. “Guys maybe recognize your pitches, your attack plan against them. That three-run home run is the one that hurt and he hasn’t been in the lineup the last few times. You just never know.’’

Pomeranz has allowed seven earned runs over 11⅓ innings in his last two starts.

“It’s a rhythm-and-timing thing,’’ he said. “I think I got out of synch a little bit for a couple of starts here.’’

The Sox have a day off on Thursday, which will give Pomeranz­ an extra day of rest.

“Work on getting that rhythm back,’’ he said.

The offense was an issue, too. The Sox stranded runners in scoring position in the first and fourth innings against Tanaka, who scattered five hits, walked two, and struck out three.

The Sox were 0 for 4 with runners in scoring position and are 0 for 15 in the series. They are 19 of 128 (.148) against the Yankees for the season.

Against other teams, the Sox have hit .289.

The Sox have lost six of their last 10 games, stumbling after three weeks of what was their best ball of the season. But they have Chris Sale on the mound Sunday night, then a nine-game, 11-day homestand starting on Monday.

They lead the Yankees by 4½ games in the division.

Peter Abraham can be reached at pabraham@globe.com. Follow him on Twitter @PeteAbe.