Team president Bill Polian released a statement Monday evening saying that the Manning had a procedure earlier today.
"Peyton Manning had an infected bursa sac removed from his left knee this afternoon," Polian said. "The procedure was routine. The Colts' medical staff expects a full and complete return to action in four to six weeks."
Polian added that the knee had been bothering Manning since the end of the 2007-08 season and only recently escalated, requiring surgery.
"Peyton had been receiving conservative treatment for an inflamed bursa sac in consultation with the club's medical staff since February, 2008," Polian said in his statement. "This course of treatment was productive until Peyton experienced increased pain and early signs of infection. Peyton will meet with the press as normally scheduled at the opening of training camp."
The Colts open training camp July 24 at Rose-Hulman Institute of Technology.