INDIANAPOLIS -- Tony Dungy is certain Peyton Manning's left knee will be ready for the Colts' season-opener.

Heck, the Colts coach said he thinks Manning might even play during the presesason.

On Tuesday, Dungy said he was optimistic the Colts' biggest question heading into training camp -- Manning's valuable knee -- could be resolved quicker than most people expect. Manning had surgery last week to remove an infected bursa sac, a procedure doctors said would require four to six weeks to heal.

Typically, Dungy defers to the medical experts on injury matters, but the Colts' Super Bowl-winning coach knows Manning well enough to realize keeping Manning off the field for six weeks may be tougher than the rehab process.

"I have talked to Peyton and we're just following the doctors instructions right now," Dungy said. "I'm hoping for four weeks, but if he's truly out six weeks, I think it will be hard to keep him out. However it goes, he'll be ready when he comes back."

Manning has not spoken publicly since having surgery last Tuesday and is expected to take questions Thursday when the Colts report to Rose-Hulman Institute of Technology in Terre Haute, Ind.

Over the past decade Manning has earned a reputation as one of the league's best and most durable quarterbacks. He has started all 160 regular-season games in his 10-year career, the second-longest streak of any quarterback in NFL history behind Brett Favre's record of 253. Manning has never missed a playoff start, either, compiling a postseason record of 7-7, and has missed only one play in his pro career because of injury.

It's not the first time Manning has battled a bursa sac injury.

During the SEC championship game of his senior season at Tennessee, Manning ruptured a bursa sac in his right knee then played through the injury in the Orange Bowl. He was later hospitalized when it became infected but showed no ill-effects; he produced the best statistics of any rookie quarterback in league history.

Still, this is the first time Indy enters camp with any questions at quarterback since Manning's five-day contract holdout in 1998, his rookie season.

But Manning's absence may have less effect this summer since Dungy, offensive coordinator Tom Moore and associate head coach Jim Caldwell had already decided to limit how many snaps the 32-year-old Manning would have in camp.

"It may be a blessing in disguise because Tom, Jim and I talked in June about giving Jim (Sorgi) some extra work with the first group anyways," Dungy said. "Peyton would like to take every snap, but Jim (Caldwell) has scaled it back every year. It would be optimal to get a couple of weeks in, but if not I think we'll be able to go."

Manning won't be the Colts' only prominent player missing from Friday's first practice.

Dungy expects four other starters to join Manning on the PUP list -- safety Bob Sanders, last year's NFL defensive player of the year; defensive end Dwight Freeney, the 2004 NFL leader in sacks; guard Ryan Lilja and linebacker Tyjuan Hagler. All are expected to be ready for the season-opener, Sept. 7 against Chicago.

The good news is that Indy now expects record-setting receiver Marvin Harrison to be available for practice. Harrison missed most of last season with a left knee injury, had arthroscopic surgery on his right knee in January and also was expected to open camp on the PUP list.

"The last I heard from the doctors meeting was that Marvin would be ready to go," Dungy said of his 35-year-old receiver. "He's been running and feeling good and everyone is optimistic."

The optimist in Dungy also anticipates a rash of rookie signings before Thursday's midafternoon reporting deadline.

On Tuesday, sixth-round pick Pierre Garcon, a receiver, became the first of Indy's nine draft picks to sign. Terms of the deal were not disclosed. The Colts also appear close to an agreement with their top pick, offensive lineman Mike Pollak, who was taken late in the second round.

"Things are going smoothly and we expect him to be in camp on time," said Ken Zuckerman, Pollak's agent.

Dungy said another sixth-round pick, Tom Santi, is expected to open camp on the PUP list because of an infected bursa sac. But for everyone other than Dungy, the biggest concern is Manning's left knee.

"Santi has a bursa sac infection too although his didn't get quite the national attention Peyton's did," Dungy joked. "My biggest concern is that we don't take things for granted. I think if we focus in, our talent level will be good enough to make us a good team."

Copyright 2008 by The Associated Press