Larry Walker, who spent the off-season rehabilitating from surgery, has once again injured his left groin.

With one check swing, Larry Walker ruined 11 days of rest. In his first game since March 8, the Rockies right fielder aggravated his strained left groin, creating the possibility he won't be available for opening day.

"Are we back to square one? I am not sure yet," trainer Tom Probst said.

Walker grimaced during his second at-bat while striding to swing. He grounded out to second base on the next pitch, jogged slowly down the line, then exited to the clubhouse, where the team doctor examined him.