NEW YORK — Manny Ramirez was not in Boston's starting lineup Wednesday night because of a strained muscle on his left side, and the Red Sox slugger likely will be sidelined for several days.

Ramirez came out of Tuesday night's game against the New York Yankees in the seventh inning after aggravating the injury. He was examined by two doctors Wednesday and wasn't sure how long he might be out.

"I don't know. Maybe a week?" Ramirez said.

Red Sox manager Terry Francona acknowledged Ramirez almost certainly would miss the final two games of the Yankees series and probably won't be available until at least Friday night against Baltimore.

"I hate to say he's not going to play before we need to, but that's realistic," Francona said. "He showed up early today — pretty sore. It's not worse than he was yesterday, which is good."

Eric Hinske started in left field for the Red Sox and batted ninth. Mike Lowell moved up to the cleanup spot. Boston began the night with a seven-game lead in the AL East over the Yankees.

Ramirez hit his 20th homer of the season in the series opener Tuesday. He is batting .292 with 86 RBIs and 32 doubles.

Ramirez, who grew up near Yankee Stadium, has always been a nemesis for New York. He is hitting .479 with 11 home runs and 30 RBIs in 27 games against the Yankees since the start of 2006.

He also has 52 career homers against New York, tied with Red Sox Hall of Famer Carl Yastrzemski for fourth-most by a Yankees opponent.

New York manager Joe Torre said facing the Red Sox without Ramirez makes "a huge difference."

"There's two reasons: First of all, you don't have Manny. And then you don't have Manny sitting behind (David) Ortiz," Torre said.

Ramirez was replaced in left field Tuesday night by Bobby Kielty, who was then removed in the eighth inning due to a sore lower back.

Kielty had X-rays on Wednesday, which were negative. His back has been bothering him since he crashed into the low fence at Fenway Park to make a terrific catch against the Los Angeles Angels on Aug. 19.

"If he needed to play tonight he could, but we'd rather not," Francona said. "There are days like today when you are glad to have Hinske."

MUSSINA YANKED FROM ROTATION: Mike Mussina is out. Call up another kid.

The New York Yankees dropped a struggling Mussina from their rotation Tuesday, turning to touted prospect Ian Kennedy over a pitcher with 247 major league wins — in the middle of a pennant race.

Bold move. But not out of character for the Yankees lately.

Kennedy, who spent most of last year playing college ball at USC, will be called up from the minors to start in Mussina's place Saturday against last-place Tampa Bay. He'll join a pitching staff that already features rookies Phil Hughes, Joba Chamberlain and Edwar Ramirez in key roles.

DANKS READY FOR FIRST START: John Danks finally gets to start a game in Texas — for the Chicago White Sox against the team that drafted him in the first round four years ago.

The 22-year-old left-hander and Texas native was the Rangers' top pitching prospect when they traded the left-hander for Brandon McCarthy last winter, two days before Christmas.

BEDARD TO MISS START: Orioles left-hander Erik Bedard will miss his scheduled start in Boston on Saturday because of a strained muscle in his right side, Baltimore manager Dave Trembley said Wednesday.

Bedard, the AL strikeout leader, is not expected to miss more than one turn in the rotation.

DODGERS CLAIM RHP LOAIZA: The Los Angeles Dodgers claimed right-hander Esteban Loaiza off waivers from the Oakland Athletics on Wednesday, assuming more than $8 million in guaranteed salary.