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05/15/08 4:29 PM ET

A-Rod given go-ahead to begin rehab

Yanks hope third baseman will be back in lineup on Tuesday

ST. PETERSBURG -- Alex Rodriguez pushed his strained right quadriceps around the bases at an estimated 95 percent on Thursday, satisfying the Yankees that the three-time MVP will be able to play in rehab games this weekend.

Rodriguez is expected to be cleared to play in extended Spring Training games and remains on track to rejoin the Yankees on Tuesday in New York.

"You want to get better every day," Rodriguez said. "It's an injury that heals with time and right now it's just getting my confidence and getting some games in, and getting some at-bats under my belt. We'll go from there."

Rodriguez simulated his normal running movements in an afternoon workout at Tropicana Field, starting at home plate with phantom swings, legging out six singles, two doubles and going from first base to third base without trouble.

"He looked fine. I didn't see anything where he was dragging his leg," Yankees manager Joe Girardi said. "That's how I would expect him to run."

Rodriguez called the test "a relief," but said it was about what he expected. He has been on the disabled list since April 30 with a Grade 2 strain that has since improved markedly. He will go through a light workout Friday and would play third base on Saturday at the Yankees' Minor League complex, logging four to five at-bats.

The Yankees do not have an extended Spring Training game on Sunday, so Rodriguez would simulate that action before playing in one more game on Monday -- a final test before his possible activation on Tuesday vs. Baltimore.

"If everything comes out fine, it's very realistic," Girardi said. "We're being very cautious, because if you have a setback now, you're talking about four weeks."

The Yankees' main concern is the first aggressive burst Rodriguez would make after jumping out of the batter's box at game speed, which was how he aggravated the injury in Baltimore.

Rodriguez sustained the injury running out a ground ball on April 20 at Baltimore. He aggravated the quadriceps when he returned to the lineup after missing three games, and has not played since April 28.

"At some point, you've just got to trust it and go all out," Rodriguez said. "That's just the way I've always played the game. That's why I think the doctors took an extra three or four days to make sure we get this thing healed up so we can go."

In other injury updates, catcher Jorge Posada (right shoulder tendinitis) threw from as far as 75 feet on Thursday with better velocity, and Girardi said Posada is "going in the right direction." Posada remains on track to rejoin the Yankees sometime in early June.

Additionally, right-hander Jeff Karstens (strained groin) threw his final extended Spring Training tuneup on Wednesday, hurling 56 pitches in five innings. Karstens' next start will come on Monday for Class A Tampa of the Florida State League as he works toward a possible big league callup.

Bryan Hoch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.