It has been an interesting offseason for the Colts’ offensive line.

Peyton Manning and Jeff Saturday are entering their 12th season together. If Saturday misses the season opener it will be a big blow for the Colts.

Coach Howard Mudd retired, starting guard Ryan Lilja was cut, and owner Bill Polian criticized the unit for its Super Bowl performance.

Things recently got more interesting.

Center Jeff Saturday (knee surgery) and left tackle Charlie Johnson (foot injury) – both starters – are now on the shelf. Colts’ owner Jim Irsay said Saturday could be out 2-6 weeks while no timetable has been given for Johnson.

Currently right tackle Ryan Diem looks to be the unit’s only sure starter for the Colts’ regular-season opener. From there, things get a bit cloudy.

“It does indeed make you work a different angle, but for the most part I think we’ve been here before,” Colts coach Jim Caldwell said.

The Colts have two viable options for Saturday’s replacement.

Third-year man Jamey Richard played center with the first team Wednesday. As a rookie in 2008, he filled in for an injured Saturday to begin the season.

“In 2008 we had to play without him as well and Jamey Richard stepped in and did a good job,” Caldwell said. “We’ll be happy to get him back, but right now we have to get ready to move forward.”

Guard Mike Pollak – the Colts’ second-round pick in 2008 – played center in college and would welcome a shift back to his old position. He played center with the second team Wednesday.

“I’m comfortable there because I played my college career there,” Pollak said. “But I also feel like I’ve got the guard down. I feel like I’ve finally gotten comfortable in that position too.”

Tony Ugoh seems to be the natural replacement for Johnson at left tackle. In three seasons with the Colts he has started 27 games at

Many consider it a make or break season for Tony Ugoh. He has a golden opportunity to make his way back into the starting lineup.

the position.

Prior to Johnson’s injury Ugoh had been shifted to left guard, but he was back with the first team at left tackle Wednesday.

The Colts often target linemen capable of playing multiple positions. The strategy appears to be paying off as the shuffling game continues.

“I think we do a good job preparing for it with guys playing multiple spots,” Richard said. “It’s a good opportunity for guys to get better and be ready for situations like this.”

Saturday missed four games during the 2008 season and the Colts’ offense struggled, scoring 18 points or fewer in three of those contests.

“He’s the foundation of our o-line,” Colts tight end Dallas Clark said. “Just what he brings with his consistent level of play and leadership, all the intangibles about Jeff are invaluable.

“It will definitely be tough without him. We will be fine, but will look forward to have him come back and hope his rehab goes well.”