INDIANAPOLIS - Bob Sanders' big hits have finally paid off in a big way. The two-time Pro Bowler signed a five-year contract extension Friday, a deal that will keep him with the Indianapolis Colts through 2012 and makes him one of the league's highest-paid safeties.

Indianapolis Colts safety Bob Sanders (21) celebrates with cornerback Marlin Jackson (28) after incepting a pass during the first quarter of an NFL football game against the Houston Texans in Indianapolis, in this Dec. 23, 2007 file photo. The revamped Colts secondary ranks No. 1 against the pass, a significant number considering it will take a statement game and perhaps a little help from Mother Nature to contain the New England Patriots' vaunted passing attack. (AP Photo/Darron Cummings, File)

The deal is worth $37.5 million and includes $20 million in guarantees, a person familiar with the negotiations told The Associated Press on condition of anonymity because the deal had not yet been announced.

Sanders' average salary of $7.5 million under the extension is nearly $1 million more than what Pittsburgh's Troy Polamalu got in his new deal in July, and the guaranteed money is more than what Ed Reed got when he signed an extension with the Ravens in June 2006.

Colts spokesman Craig Kelley said the team would not confirm the deal, but Sanders told The Associated Press in a telephone interview that he had signed the deal Friday.

His contract was to expire after this season.

"I got a call late in the evening yesterday from my agent and he said he was hoping to get it done," Sanders said. "I'm excited, very excited about it — knowing they want me around here makes me happy."

Sanders is one of the top candidates for NFL defensive player of the year. Coach Tony Dungy calls him "The Eraser" for his ability to cover up mistakes.

He's also the heart of the Colts defense.

Last year, when Sanders missed 12 regular-season games, the Colts allowed a league-worst 5.3 yards per carry. When he returned in the playoffs, the Colts made a dramatic turnaround and wound up winning the Super Bowl. Sanders received much of the credit.

This year, with Sanders missing just one game because of injury, the Colts defense ranks No. 1 in the league against the pass and has allowed a more respectable 3.9 yards per carry.

But Sanders had a bigger personal goal this year: staying healthy.

"It was just about being a player, being competitive," he said. "I wanted to show everyone I could stay healthy. There were a lot of questions about whether I could stay healthy and I wanted to prove to everyone and myself that I could stay healthy, be consistent and play well."

With Sanders playing closer to the line of scrimmage, almost as a linebacker for much of the season, he has 123 tackles, 2 1/2 sacks, two interceptions and one forced fumble.

But his impact cannot be measured solely in numbers.

When defensive end Dwight Freeney went down with a season-ending foot injury in mid-November, Sanders became the defense's uncontested leader and the results have been impressive.

"When you think of a defensive player of the year, you usually think about someone who really is a dominant player, who makes big plays and is a game changer. You don't usually think of it being a secondary guy," Dungy said Monday. "Occasionally it is, but you think of guys like Lawrence Taylor and Mike Singletary. Bob has definitely been a game-changer for us."

Sanders now joins an exclusive club of well-paid Colts (13-2).

Two-time league MVP Peyton Manning signed a $98 million contract in March 2004, and perennial Pro Bowl receiver Marvin Harrison got a $66 million deal nine months later. Two-time Pro Bowl receiver Reggie Wayne agreed to a $39 million contract in 2006, and in July, Freeney, a three-time Pro Bowl pick, was rewarded with a six-year, $72 million deal — the highest annual average of any NFL defender.

"When you come in, it's hard but you've got to prove yourself and play well consistently," Sanders said. "Just to be named with those guys, I'm honored. It's a great honor."

The move also helps Indianapolis on another front.

Dallas Clark, yet another key component in the Colts' high-scoring offense, also is scheduled to become a free agent after the season. Clark, a first-round pick in 2003 and a college and pro teammate of Sanders, has already set single-season franchise records this year for receptions (57) and touchdown receptions (11) by a tight end.

With Sanders now under contract, the Colts could use the franchise tag to keep Clark in Indianapolis, too.