INDIANAPOLIS – Bill Polian made one big mistake in Indianapolis: not having an adequate backup for Peyton Manning.

It cost the Colts vice chairman and his son their jobs.

On Wednesday, Polian told The Associated Press that not grooming a replacement for the injured Manning was the primary reason the Colts collapsed this season, going from Super Bowl contender to the league’s worst record.

“I’ve always told the staff that our approach should be to hope for the best but plan for the worst, and I didn’t do an adequate enough job of planning for the circumstances we were in,” Polian said in a phone interview. “It led to this catastrophe.”

When asked if he was referring specifically to finding a backup for Manning, Polian said: “yes.” It’s the first time Polian has commented since he and his son, general manager Chris Polian, were fired Monday.

The longtime NFL executive revived the Colts’ brand name in two seasons, turning a moribund organization into one of the league’s model franchises. During Polian’s 14-year tenure, the Colts won 143 regular-season games, eight division titles, two AFC crowns and the first Super Bowl championship in the Indianapolis era.

Even all that couldn’t save Polian after a 2-14 record gave Indianapolis the No. 1 draft pick.

“I understand what the dynamics are. So when you have the kind of season we had, there’s always some accountability and that includes me,” Polian said. “Was I surprised? No. The timing of it was a bit surprising, but not the end result.”

Manning’s neck injury changed everything.

The four-time league MVP never played after undergoing surgery Sept. 8, his third and most invasive procedure in 19 months. With Manning out, the Polians scrambled.

First, they brought 17-year veteran Kerry Collins, who Polian originally drafted in Carolina, out of retirement for $4 million. Collins didn’t last a month. Curtis Painter, Manning’s backup the previous two seasons, replaced Collins as the starter in Week 4 but struggled.

Still winless heading into December, the Colts finally turned to seven-year NFL veteran Dan Orlovsky, who ended a nine-game personal losing streak with two wins in five days just before Christmas.

But more could have and should have been done, Polian said.

“We probably could have straightened out the defensive situation a little earlier than we did, but that wasn’t critical,” Polian said, referring to the November firing of defensive coordinator Larry Coyer. “We needed to have a guy in place if Peyton had gone down and we didn’t. It wouldn’t have been a playoff season, I don’t believe, if we had. But I didn’t do it.”

Polian called “completely untrue” a rumored rift between himself and Manning.

“He was the first person into the office after it happened,” Polian said. “There’s no rift at all. None.”

In fact, Polian said, the two were speaking in the training room about Manning’s offseason rehab plan when Irsay called him into the office. The two Polians then met separately with Irsay, and afterward, Bill Polian said, he and Manning talked for another 45 minutes. Polian declined to provide details of that discussion, calling it private.

Does Polian believe Manning will play again in 2012?

“I don’t know. I can’t answer that,” he said.

For Polian, the hardest part wasn’t getting fired. It was seeing his son lose his job.

Notes: The Colts won’t bring back special teams coordinator Ray Rychleski next season. Indianapolis ranked last in the league in kickoff return average (18.6 yards) and punt return average (3.4). … The Colts also signed tackle Mike Tepper, defensive tackle Ollie Ogbu and offensive guard Matt Murphy to future contracts.