LONDON — Reggie Bush had surgery on his left knee and it's unclear when the New Orleans Saints running back will be back with the team.

Bush, injured on a punt return in the first half of Sunday's 30-7 loss to the Carolina Panthers, had the operation Monday in Birmingham, Ala., Saints spokesman Greg Bensel said Tuesday in an e-mail to The Associated Press. He gave no other details.

Instead of accompanying his teammates on the trip to London to face the San Diego Chargers on Sunday at Wembley Stadium, Bush instead visited Dr. James Andrews.

"He has been a big part of what we have been able to do offensively and it's an injury that we have to deal with," Saints coach Sean Payton said shortly after the team arrived Monday. "Hopefully on a short-term basis rather than a long-term basis, and it sounds like that's the case."

Bush sustained cartilage damage, and some athletes have missed several months because of surgery to repair similar injuries.

"From a timing standpoint, it falls with this game and then a bye weekend, so there is a little bit of time there for him as it pertains to his recovery," Payton said. "We'll have to make some adjustments offensively."

Aaron Stecker or Pierre Thomas will be called on to play alongside Deuce McAllister in the backfield.

The Saints played the final four games of last season without Bush due to a knee injury, and they went 2-2.

"Hopefully we won't skip a beat," Saints quarterback Drew Brees said. "Obviously we will miss Reggie, just like we will miss any guy who is that productive for us offensively."

Bush entered the game against Carolina with an NFL-best 41 receptions.

The 2005 Heisman Trophy winner from Southern California missed practice early last week with swelling in his left knee. He had 55 yards on nine carries, caught one pass for 5 yards, and had a 3.5 average on three punt returns against Carolina.

Still, Brees appeared confident for the game against the Chargers, who are also 3-4.

"I feel like Deuce is running the ball very well right now," he said. "Whoever we put back there I have a lot of faith in."