BOSTON – Add another one to a list of key injuries for the New York Yankees.

Manager Joe Girardi expects leadoff hitter Brett Gardner will be out for a lengthy stretch and possibly the rest of the regular season.

Girardi made the announcement before New York opened a three-game series with the Boston Red Sox at Fenway Park on Friday night.

Gardner left Thursday night’s win in Baltimore with the injury, which Girardi said is a “Grade 1 strain in his rib cage.” He’s batting .273 with eight homers and 52 RBI, and a big part of New York’s injury-ravaged offense.

“He’s going to be out a while,” Girardi said. “Rib cages don’t heal real quick. It’s not like it’s just a few days. Is it possible it could be the rest of the year? Yeah.”

It’s the latest in a season filled with injuries for the Yankees, who are two games back in the AL’s wild-card chase.

“I’m almost at the point where I don’t think it surprises our guys anymore,” Girardi said. “I don’t want to diminish how important guys are to us, but we’ve kind of gotten used to it. A guy comes back, a guy goes down. That’s kind of how it’s been all year long.”

BLUE JAYS: Slugger Edwin Encarnacion returned to the lineup for the game against Baltimore, and outfielder Colby Rasmus was activated off the 15-day disabled list to start against the Orioles.

Encarnacion is batting .276 with 36 home runs, the third-highest total in the major leagues, while his 104 RBI are the fourth-most. He returned as the designated hitter after missing the past four games with a sore left wrist.

Rasmus, who is hitting .273 with 18 homers and 60 RBI, has been out since Aug. 11 with a strained muscle in his left side. He started in center field.

BREWERS: Aramis Ramirez left the game after being hit in the left wrist by a pitch from Mat Latos of Cincinnati.

The Milwaukee third baseman grimaced and immediately grabbed his hand. He was replaced to start the second inning by Jeff Bianchi.

Ramirez has missed 54 games during two stints on the DL this year because of a left knee injury he suffered in April. He is batting .267 with 10 home runs and 41 RBI in 81 games.

NATIONALS: Right-hander Stephen Strasburg was scratched from his scheduled start against the Philadelphia Phillies because of tightness in his forearm.

The Nationals are opening a 10-game homestand with Ross Ohlendorf (3-0) starting in Strasburg’s place.