INDIANAPOLIS (AP) — Peyton Manning is healthy enough to start playing games.

Now the Colts must find out how well his left knee will hold up to the hits.

Indianapolis coach Tony Dungy reiterated Monday that Manning would probably start Sunday night's season-opener against Chicago, perfect timing for a starting offense that failed to score a single touchdown in five preseason games.

"I'm sure he'd rather have gone through training camp and gotten his normal reps," Dungy said. "But we've done it before with Bob Sanders, so I don't worry about it with a veteran guy. If he was a second-year guy, you might."

Manning has eased his way back into a normal routine last week, more than a month after having surgery to remove an infected bursa sac from his left knee.

He started practicing last Tuesday, increased the workload Wednesday, then went through his regular pregame routine before Thursday night's preseason finale against Cincinnati — the first time Manning was even in uniform for a game though he still sat out.

Since there have been no setbacks, Dungy now expects Manning to use this as a regular week before making his season-debut Sunday. It will allow Manning to keep the NFL's second-longest streak for consecutive starts by a quarterback (160) intact. Only Brett Favre, who has taken his record streak of 253 from Green Bay to New York, has more.

Manning didn't speak to reporters Monday but is expected to take questions Wednesday.

Of course, Manning's injury isn't the only concern for Indy. His longtime backup, Jim Sorgi, missed the last two preseason games with a gimpy knee and his replacements, Jared Lorenzen and Quinn Gray, struggled. Lorenzen and Gray were cut Saturday.

Indy took one precaution Monday by adding a third quarterback to the roster, Josh Betts, who is starting his third straight season on the Colts' practice squad.

"I've been working out during the week and going to the lake on weekends," said Betts, who was released at the start of training camp. "I've been throwing three or four times a week, and I'm real happy I got the call Saturday."

Dungy didn't announce the entire practice squad because he said all eight players had not yet been signed.

The bigger concern may be the battered offensive line.

Pro Bowl center Jeff Saturday, who makes the offensive line calls in the no-huddle offense, could miss at least six weeks after injuring a ligament in his right knee. The Colts have not given a definitive timetable for Saturday's return.

The likely replacement is Jamey Richard, a sixth-round pick in April. Dungy and the Colts aren't worried.

"He's going to step in and do a good job," right tackle Ryan Diem said. "Obviously, Jeff is a special player and he'll be hard to replace. So we've got to get him (Richard) up to speed."

Also out will be left guard Ryan Lilja, who was placed on the physically unable to perform list Saturday, and Mike Pollak, the Colts' second-round pick who was battling three-year veteran Charlie Johnson for the vacant right guard spot.

Lilja still hasn't practiced since having offseason knee surgery, and Pollak has been out since hurting his right knee against Buffalo on Aug. 24.

The replacements at guard are expected to be Johnson, a third-year player who filled in for the injured Diem during Indy's Super Bowl victory over the Bears, and Dan Federkeil. Johnson started 10 games last season in Indy; Federkeil will be making his first career start.

But the Colts have survived this way before.

"The thing about it is you can't overblow the situation," Dungy said. "The guys have to feel like they can do their job. We played with three rookies on the line against Detroit on Thanksgiving a couple of years ago, and they did their job and we put up a lot of points."

Now, though, they will be protecting Manning against a defense that typically ranks among the league's best units — and one that will try to hit Manning hard.

"We'll bump him up a little bit in practice this week," Dungy said. "But it's not like we want him getting hit anyway."