Manny Ramirez is in cruise control as circles the bases after hitting a solo home run in the seventh inning.

The Providence Journal / Bob Breidenbach

BOSTON — It was just one pitch, but it turned the course of the game.

Red Sox reliever Joel Pineiro came on with the bases loaded and one out in the seventh inning yesterday to face San Francisco Giants catcher Bengie Molina, who represented the tying run.

Before leaving him on the mound, Boston catcher Doug Mirabelli told Pineiro, “Keep the ball down and we’ll get a double play on this guy.”

Pineiro did as he was instructed, dealing Molina a low fastball, and Molina did just what Mirabelli predicted he’d do — and on the first pitch, no less. He grounded into an inning-ending double play.

Potentially damaging situation averted, and the Red Sox finished off a sweep of the Giants, 9-5, at Fenway Park.

“The game was getting a little quick there,” Boston manager Terry Francona said. “And at a key time he gets a one-pitch double play that slows everything down. That was a big point for me in the game.”

Pineiro had faced Molina before, when he was a member of the Mariners and Molina was with Anaheim. Pineiro recalled that the former A.L. Rookie of the Year was an aggressive hitter, though he believed Molina had taken him yard a few times. In truth, Molina came into the day 5-for-28 (.179) against Pineiro with just one home run.

“He’s the perfect type to double up,” said Pineiro. “I knew if he had a ground ball, one of those guys would make the play. He’s not really going to beat it out.”

When he signed a one-year deal with Boston last offseason, Pineiro was expected to be one of the main guys competing for the role of closer, since Jonathan Papelbon was slated for the starting rotation. But when Papelbon was returned to the pen, it changed things for Pineiro, who made his 25th appearance of the year yesterday.

There was another change that put Pineiro in the situation against the Giants yesterday. As he pointed out, Brendan Donnelly normally would have been brought in for that situation, but with Donnelly placed on the 15-day disabled list earlier in the day due to forearm tightness, it was Pineiro who got the call.

“There was a sigh of relief” after inducing the double play, he said. “To come on in a key situation felt good. I knew I had to do the right thing so I could go back out and get the ball again.”

Pineiro pitched a perfect eighth inning, and Hideki Okajima, on the mound for the third straight day, finished the game.

Their efforts complemented those of Tim Wakefield, who got his seventh win of the season, allowing five runs over 5 2/3 innings, including the 748th home run of Barry Bonds’ career. Bonds’ solo shot to the San Francisco bullpen led off the sixth, looked like a routine fly ball coming off the bat, but kept floating, and landed just over the wall.

Wakefield, who also gave up a home run to third baseman Pedro Feliz, felt fortunate to get help from his teammates.

“I pitched good enough to get us a win, because the offense won the game today,” said Wakefield. “I was fortunate to get the win.”

At the plate, everyone got in the act — well, at least everyone in the top two-thirds of the order — as Boston showed signs of getting out of its hitting slump.

J.D. Drew led off the game with a double to center, and before long the Sox had the bases loaded with none out. Drew came home on a double-play ball by Manny Ramirez, and Kevin Youkilis plated Dustin Pedroia with a single off the base of the wall.

But a five-run third is where Boston did most of its damage, with five players — David Ortiz (2-for-3, two doubles), Ramirez, Youkilis, Mike Lowell and Mirabelli — recording an RBI.

While batters one through six in the order went a combined 9-for-22 with all nine runs scored, Mirabelli’s single in the third was the only hit of the game among himself, Wily Mo Pena and Julio Lugo. Pena, who started the game in center so Francona could rest Coco Crisp, was replaced by Crisp for the eighth. Crisp singled in the bottom of the inning, giving him a modest four-game hit streak.

In the second, Giants starter Matt Morris got his only three strikeouts of the game, sitting down Pena (looking), Mirabelli (swinging) and Lugo (swinging) in order.

But it was easy to overlook the black hole at the bottom of the lineup when the top had it working.

“We have a very deep lineup that can do that,” Lowell said of the team’s output in the third. “It’s a plus when you can have five guys that can do that. If you have two guys on and one guy hits a three-run homer, you might start to rely on that guy too much.”

The sweep had the players in a good mood as they got ready to leave for Atlanta.

“The win makes the plane ride a lot easier,” said Lowell.

smanza@projo.com