NEW YORK – Hideki Matsui could be out until the All-Star break as the Yankees slugger tries to work his way back from a sore left knee.

General manager Brian Cashman said Wednesday that Matsui was still hobbled by the injury, which landed him on the disabled list Friday. The club had hoped he'd be ready to take batting practice this weekend, but Cashman said that timeframe is no longer realistic.

“He did some work with the physical therapist and he hasn't gotten cleared to do anything,” Cashman said. “Once the knee calms down, the swelling gets out of there, he'll start doing some work. But he's not there yet.”

Matsui had right knee surgery during the offseason, but this time it's his left knee that's causing problems. He is batting .323 with seven homers and 34 RBIs in 69 games.

The news wasn't much better for the Yankees at their top minor league club.

Shelley Duncan separated his shoulder Tuesday night making a diving catch into the warning track. He took his time getting up and immediately left the game.

Duncan hit .175 in 23 games with the Yankees before getting demoted. He was batting .243 with seven homers and 27 RBIs for Triple-A Scranton-Wilkes Barre.

Cashman said it's possible the injury could be season-ending.

“We're going to deal with some timeframe, it's just a matter of how long,” he said. “That's a lengthy injury. That's all I got right now.”

Cashman said right-hander Alan Horne also was headed for the minor league disabled list, but nothing was seriously wrong and Horne was just getting some “R and R.”

In other news, the Yankees announced they agreed to deals with four of their picks from last month's draft. Among them is ninth-round selection Michael O'Brien, a right-hander from Hidden Valley High School in Virginia.

The Yankees also agreed to deals with three players from the Dominican Republic on Wednesday: outfielder Yeicok Calderón, and shortstops Anderson Felix and Gian Arias.