Giambi tweaked the tendon during an at-bat in Sunday's loss to San Francisco. Tracy said Giambi's arm remains very sore and that he's expected to undergo an MRI soon to re-confirm the diagnosis of a strain.
"The prospects of him getting another at-bat between now and Sunday, I wouldn't think that they're very good," Tracy said.
The Rockies finish a four-game, season-ending series in St. Louis on Sunday.
Giambi has appeared in 87 games with 43 starts at first base. He is batting .244 with six homers and 35 RBIs.
Miguel Olivo, who was kicked in the head by teammate Troy Tulowitzki as they converged on a foul pop Sunday, was to take off Monday night's game against Los Angeles. Tracy said Olivo would remain available in case of an emergency. Chris Iannetta was slated to start at catcher in Olivo's place.
"That position is dangerous enough in itself but when you've got a knot on your head, you're not taking a chance on seeing how many foul tips the guy can take off the mask," Tracy said. "We're erring on the side of caution with him, knowing full well in the event of an emergency Miguel would be available. But we want to give him another day to just re-gather himself."
The Rockies were also without third baseman Ian Stewart, who stayed home ill with flu-like symptoms.