TERRE HAUTE, Ind. — Colts defensive back Michael Coe will be placed on injured reserve and will miss the rest of the season after having surgery on his left knee last week.

Coach Tony Dungy had said Coe was likely to miss at least eight weeks and Indianapolis hoped to wait until the two roster cutdowns before making a decision.

The plan changed Tuesday when Dungy announced they couldn't wait for Coe to return because they needed a roster spot.

"We wanted to hold off as long as we could, but realistically he would be out two months, so we would have had to carry 52 instead of 53 for that time," Dungy said. "It's tough because he did a great job rehabbing his shoulder, and then he had a freak injury that ruined his season."

The problem for the Colts is that they've been ravaged by injuries, including a handful to prominent players. Five starters — two-time MVP Peyton Manning, 2007 defensive player of the year Bob Sanders, former league sacks champion Dwight Freeney, left guard Ryan Lilja and outside linebacker Tyjuan Hagler — still have not practiced after being placed on the physically unable to perform list.

Manning hasn't even been on the practice field since having surgery July 14 to remove an infected bursa sac from his left knee. All except Hagler are expected to be healthy by Indy's Sept. 7 season opener against Chicago. Hagler is expected to be out until October after tearing a pectoral muscle while lifting weights this summer.

Rookie tight end Tom Santi, a sixth-round pick, is also on the PUP list after having an infected bursa sac removed from his knee. Dungy said Santi may start practicing next week.

That's just the start.

The rash of injuries has hit the linebackers hard. Defensive captain Gary Brackett and Clint Session, Hagler's backup, both missed practice time last week although they returned before Indy's preseason game at Carolina. Session did not play in that game.

Another linebacker, third-round pick Philip Wheeler, had knee surgery last week and is expected to miss a couple of weeks. Also out is backup Victor Worsley (hamstring), and the recently signed Dedrick Harrington was waived-injured Tuesday. Last week, the Colts put another recently signed linebacker, Brandon Archer, on the waived-injured list.

"Philip's doing fine, he's off the crutches and starting the rehab process," Dungy said. "We're thinking he'll be back maybe Buffalo week or if not then Cincinnati week."

Indy plays at Atlanta on Saturday, then hosts Buffalo on Aug. 24 — the first NFL game at the new Lucas Oil Stadium.

As expected, the Colts added another linebacker Tuesday night by claiming Marcus Richardson off waivers from Houston. Richardson is a 6-foot-3, 225-pound undrafted rookie from Troy State.

Indy filled Harrington's roster spot by re-signing running back Clifton Dawson, who was released Saturday to make room for kicker Adam Crossett.

Running back Kenton Keith missed both of Tuesday's workouts after hurting his hip during Monday's special teams practice. Dungy hopes to have Keith back on the field Wednesday.