Indianapolis Colts quarterback Andrew Luck remains on the physically unable to perform list and his status for the team's regular-season opener is in jeopardy.

Luck is recovering from surgery to repair a partially torn labrum in his right shoulder and owner Jim Irsay said Sunday he couldn't promise Luck would be ready to face the Los Angeles Rams on Sept. 10, though he does believe it's likely.

"I can't say unequivocally that he (Luck) will be ready for the Rams game," Irsay said. "But I can say I feel very confident that he will be ready to start the season."

Luck did not participate in any off-season workouts with the Colts and the team said he only resumed throwing in mid-July after the January surgery.

Scott Tolzein served as the starter in the Colts' first preseason game on Sunday, completing 2 of 5 passes for 24 yards.

Luck, the first overall pick of the 2012 NFL Draft, went 8-7 last season with 31 touchdowns to 13 interceptions. He completed a career-high 63.5 per cent of his passes for 4,420 yards.

He is a three-time Pro Bowler.