Boston’s Masataka Yoshida celebrates as he crosses the plate after his go-ahead home run in the eighth inning Sunday against the Oakland Athletics. Steven Senne/Associated Press

BOSTON — When the Boston Red Sox signed Japanese batting champ Masataka Yoshida over the winter, there was a lot of snickering that they had overpaid.

“I know a lot of people still have question marks,” Red Sox Manager Alex Cora said after Yoshida helped Boston win its fifth straight game heading into the All-Star break, beating the Oakland Athletics 4-3 on Sunday. “I’m glad we took a chance.”

The Red Sox had success signing Japanese players before, with Daisuke Matsuzaka helping the team win the 2007 World Series and Koji Uehara closing out the championship in 2013. Still, when they made Yoshida the centerpiece of the latest offseason by giving him a five-year, $90 million deal, the word around baseball was that they bid against themselves.

But Yoshida has been Boston’s most reliable hitter, batting .316 with 10 homers and 44 RBI heading into the break. On Sunday, he singled and scored the tying run with good baserunning, then gave the Red Sox a 4-3 lead when he bounced one off the top of the Green Monster.

“The best thing is we won the game, and then being excited together,” he said through a translator. “So that was really happy.”

The Red Sox have won eight of their last nine games since falling a season-high 15 games back in the AL East. They remain in last place in the division, but head into the break just two games out of the last wild-card spot.

“I’m glad that we ended up the first part of the season this way. We’re playing some good baseball,” Cora said. “It’s a good feeling, but we’ve got work to do. We’re still last in the American League East.”

J.P. Sears took a no-hitter into the fifth for Oakland despite allowing an unearned run in the first, thanks to one of three A’s errors. Boston trailed 3-1 in the middle of the sixth before Adam Duvall hit a solo homer to lead off the bottom half, then Yoshida singled, stole second, took third on a bad throw from catcher Manny Piña and scored on Christian Arroyo’s double to tie it.

Yoshida’s homer gave Boston its only lead.

“To end the first half with a win, it’s huge. Especially the way we’ve been playing,” Duvall said. “I think we’re getting some momentum right now, and it’s good to take that into the break.”

Brent Rooker had three hits for Oakland, including a 443-foot home run high off of the Green Monster light stanchion.

Chris Martin (3-1) pitched a scoreless eighth for the Red Sox, and Kenley Jansen – the lone Boston All-Star – pitched the ninth for his 19th save.

Ken Waldichuk (2-6) gave up Yoshida’s homer.

HARD LUCK

Sears, who picked up his only victory of the season on June 11, had a chance to snap a three-game losing streak when Oakland built a 3-1 lead.

He allowed an unearned run in the first when leadoff hitter Rob Refsnyder walked, moved to second on a wild pitch, took third on a fielding error and scored on a shallow sacrifice fly to right.

In all, Sears gave up one unearned run on one hit, three walks, two hit batters and a wild pitch. He struck out four in five innings.