Yankees right fielder Gary Sheffield will undergo surgery to repair a torn ligament in his left wrist but is not expected to miss the rest of the season, general manager Brian Cashman said yesterday.

The surgery will be performed on Tuesday by Dr. Charles Malone and will sideline Sheffield until September at the earliest.

Sheffield originally hurt the wrist when he collided at first base with Shea Hillenbrand of the Toronto Blue Jays on April 29. He missed three games, returned for two games, and then went on the disabled list May 9 with a contusion and sprain of the wrist and missed 16 games.

He returned on May 23, made five starts as a designated hitter, and then returned to right field on May 29. Two days later, he went back on the DL with the ligament tear.

“I am told it’s not a season-ending injury,” Cashman said before the Yankees’ game last night against Boston. “He experienced worse pain after he tried to come back. Surgery is being recommended. It wasn’t an option earlier.”

The Yankees are already without left fielder Hideki Matsui, who had surgery on a broken left wrist after injuring himself diving for a ball hit by Boston’s Mark Loretta on May 11.

Manager Joe Torre learned about Sheffield’s surgery two hours before last night’s game against Boston.

“Sheff’s in great shape,” he said. “It’s all about how quickly he can heal. I knew the possibility of surgery existed so it doesn’t surprise me. What I get from this, there doesn’t seem to be any doubt that he’ll be fine.”

With Matsui and Sheffield sidelined, the Yankees have used rookie Melky Cabrera and veteran Bernie Williams to replace them. Cabrera made a game-saving catch, robbing Manny Ramirez of an eighth-inning home run on Tuesday.

“Right now, we’re a little thin,” Torre said. “We’re going out every day and finding a way to win. We’ve been pretty fortunate lately.”

Sheffield’s surgery comes with him five RBI away from 1,500 for his career. He would be the 44th player in major league history to reach that plateau. This season, he is batting .309 with four homers and 19 RBI in 30 games.

Shortstop Derek Jeter missed his third consecutive game last night because of a sore right thumb after being hit by a pitch by Baltimore’s Rodrigo Lopez on Sunday.

“He’s better,” Torre said. “He says it’s feeling better. As long as he’s getting better, that’s the important thing. We’ll get him back whether it’s tomorrow or the next day. Whenever it is, we’ll get him back.”