A week ago, Archie Manning was talking about how you learn to expect the unexpected in college football.

“Somebody told me a long time ago that that thing is oblong, so it bounces funny,” he said. “You don’t know who’s going to beat who or who’s going to get hurt or who’s going to get suspended. There are a lot of things that can happen.”

Just as unexpected: Manning going on the College Football Playoff selection committee’s version of injured reserve.

The former Ole Miss and New Orleans Saints quarterback is taking a leave of absence from the group because of lingering problems from knee replacement surgery that made travel to the weekly committee meetings — which begin next Monday in Dallas — extremely uncomfortable. Manning also has been slowed by back surgery he had in 2012.

The pain prevented Manning from being in Denver on Sunday night to witness his son Peyton become the NFL’s career touchdown pass leader.

Archie was at Saturday’s Ole Miss-Tennessee game in Oxford, Mississippi, where he owns an on-campus condo. He had said he hoped to attend this Saturday’s Ole Miss-LSU game — the first time the Rebels and Tigers have met as ranked teams in Tiger Stadium since 1970, when Manning was a senior.

And, as recently as last week, he talked about how rewarding being on the committee had been, with no hint that he might have to relinquish his spot.

“It’s been an honor to serve on this committee,” Manning said in a statement. “I enjoy the group and was looking forward to the opportunity ahead. My health has to be my primary concern, and I intend to be up and about as soon as possible.”

Manning’s decision left the committee with 12 members. CFP Executive Director Bill Hancock said that because the season is half-over, there will be no replacement.

Although Manning unofficially was the SEC representative to the group, Arkansas Athletic Director Jeff Long is the chairman.

All of the committee members had been assigned conferences to concentrate on. Former Big East Commissioner Mike Tranghese will join West Virginia Athletic Director Oliver Luck on the Mountain West, and former college football reporter Steve Wieberg will assist longtime NCAA administrator Tom Jernstedt with the ACC.

“We will miss Archie,” Hancock said. “He has a great knowledge of college football and history of the game. But we all understand his reason for taking a leave. I wish him all the best and look forward to his return in 2015.”

The committee’s first rankings will be issued Oct. 28. The four playoff teams, including the semifinalists who will meet in the Sugar Bowl, will be announced Dec. 7 along with the teams in the other four CFP bowls.