Rodriguez suffered the injury legging out a fielder's choice in the Yankees' 5-1 victory over the Minnesota Twins on Monday. Rodriguez briefly stayed in the game before being lifted for pinch-runner Miguel Cairo.
It was not immediately clear if Rodriguez -- the Major Leagues' leading vote-getter for the July 10 All-Star Game, garnering more than 3.8 million votes -- would be sidelined, or for how long.
"I'm not thinking about that right now," Rodriguez said. "I'm just hoping in the morning [I wake up] and I can put some weight on it and go from there."
The strained hamstring was diagnosed by team physician Dr. Stuart Hershon. The Yankees said that Rodriguez is scheduled to be re-evaluated on Tuesday, and manager Joe Torre remained optimistic that the slugger could sidestep a trip to the disabled list.
"I think [Tuesday] will tell us more than anything I could tell you now, because I'd be guessing," Torre said. "That's certainly not one of my guesses right now. I don't want to be thinking that."
"From what I understand, I don't think it's that bad," Derek Jeter said. "I don't think they'll know until tomorrow. Hopefully it's not anything that's going to take a while."
The play occurred in the sixth inning, when the Yankees sent 10 men to the plate and scored four runs to back Roger Clemens' 350th career victory. Facing right-hander Matt Guerrier, Rodriguez chopped a one-out grounder to third base.
Hustling down the line to beat out a potential double play, Rodriguez made a final lunge toward the first-base bag. His left leg connected briefly with Twins first baseman Justin Morneau's right leg; Rodriguez then stumbled and rolled after hitting the base, breaking his fall with his hands.
As he rose, Rodriguez immediately favored his left leg. Television replays showed him holding the area behind his left kneecap, near the hamstring.
Rodriguez was attended to on the field after the play and briefly ran a sprint down the right-field line, wincing but convincing manager Joe Torre to allow him to stay in the game.
Rodriguez's time was limited. After moving up on a Jorge Posada walk, third-base coach Larry Bowa ran out to second base and called Torre and trainer Steve Donohue back on to the field, deciding to remove the 11-time All-Star from the game. Rodriguez said he told Bowa he would have been unable to score if Hideki Matsui got a hit.
"I just knew that on a ball hit to the outfield, there was no way I was going to score," Rodriguez said. "I was definitely scared to bust it and really pull it and miss a lot of time. Bowa thought it was a smart idea to go put some ice on it."
Despite the strained hamstring, Rodriguez said he was thankful he had avoided a more violent collision with Morneau.
"It was kind of an awkward play, you know?" Rodriguez said. "Two big guys banged up each other pretty good right there. I think we're both fortunate, because it could have been ugly, for him and for me."
"In his particular case, it looked like he was trying to avoid a collision," Torre said. "That's what may have caused that. But nobody, as far as conditioning, does all the right things better than he does, as far as stretching and his program before he goes on the field. It's just a screwy move that causes you to surprise your body a little bit."
The strained hamstring is the second in Rodriguez's career, having suffered a similar injury in April 1996 as a member of the Seattle Mariners. That incident was more severe than Monday's, as Rodriguez could not leave the field under his own power. He was on the disabled list then for two weeks.
"I couldn't even walk off the field [in 1996]," Rodriguez said.
The Major League leader with 28 home runs, 79 RBIs and 74 runs scored, Rodriguez is batting .322 with a big league-leading .680 slugging percentage in 80 games for New York this season.
Losing Rodriguez would be a crushing blow to a Yankees team that has struggled with various injuries all season long and is hoping to resuscitate its fading postseason hopes; the club's victory over the Twins improved New York's record to 38-41, 11 games behind the American League East-leading Boston Red Sox.
"I'm concerned. [Darn] right I'm concerned," Torre said. "I just hope it's not going to be a long-term thing for us."
Bryan Hoch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.