BOSTON (AP) — Jon Lester is proving he’s Boston’s ace again.

Lester pitched eight dominant innings, and the AL East-leading Red Sox dealt the New York Yankees’ wild-card hopes another blow with a 5-1 win on Saturday.

The 29-year old left-hander is 6-3 since mid-July with a 2.52 ERA in 12 starts after a rough stretch midway through the season.

“What he’s done since the All Star break has been consistent with how he’s started the season,” Red Sox manager John Farrell said. “A well above-average pitcher, a front-line starter and that’s what Jon Lester is.”

Lester (14-8) was solid from the start, mixing a sharp cutter with a well-spotted, mid-90s fastball. He allowed one run and three hits, striking out five and walking two for his fourth win in six starts.

Midway through the season, he went 0-4 in six starts with a 7.20 ERA.

“I knew after what I went through at the middle of the year that it’s just a matter of time and things will take care of itself,” he said. “I think anytime you take someone that’s had some success, your confidence is high. When you struggle, that kind of varies from certain starts.”

Mike Napoli, Jonny Gomes and Shane Victorino each had two hits as the surging Red Sox won for the 16th time in 19 games, and beat the Yankees for the fifth time in six meetings in just over a week.

Napoli, in his first season with the Red Sox, has seen the best of Lester from the opposite side.

“I remember facing him when he had his changeup, it’s tough because he’d throw that cutter in on your hands and a changeup strike when he’s just pounding you inside all the time,” he said. “He’s been doing great. You can see he’s confident out there. He’s just getting the ball and throwing.”

The Yankees lost their second straight after a three-game winning streak and fell 2 1/2 games behind Tampa Bay for the AL’s second wild-card spot. The Rays play at Minnesota on Saturday night.

“You have to find a way to get it done is the bottom line,” New York manager Joe Girardi said of facing Lester. “He’s been throwing the ball well. He threw it well against us last time and he did it again today, but you’ve still got to find a way.”

Boston entered the day with an 8 1/2-game lead over second-place Tampa Bay.

The Red Sox (91-59) improved to a season-high 32 games over .500, their best mark since the final day of their World Series championship season in 2004.

Franklin Morales worked a perfect ninth.

For the second time in week, Boston goes for a sweep against New York. Last weekend, the Red Sox won the initial three of a four-game set at Yankee Stadium but lost the finale.

The Red Sox built a 5-1 lead against CC Sabathia (13-13) after five innings.

“I felt like I was behind everybody and got into some tough counts,” Sabathia said. “With a team like they have, when you get behind and in a hitter’s count, you’re going to give up some hard-hit balls.”

Will Middlebrooks’ run-scoring grounder gave Boston a 1-0 edge in the second. Napoli singled before moving up on a walk and sacrifice.

In the third, David Ortiz had an RBI double and Gomes added a run-scoring single. Sabathia then fanned the next two hitters with runners on first and third.

Lester breezed through the first nine batters, holding the Yankees hitless before Curtis Granderson tripled off the center field wall leading off the fourth. He scored on Robinson Cano’s bouncer to first to make it 3-1. But Victorino had a two-out RBI single in the bottom half.

Sabathia went six innings, allowing five runs on nine hits, walking four and striking out five. He’s 4-6 with a 6.48 ERA in his last three seasons against the Red Sox.

Daniel Nava’s sacrifice fly increased it to it 5-1.