INDIANAPOLIS — Next man up.

That’s been the philosophy all season for the Indianapolis Colts — a philosophy that every man on the roster plays an important role. A philosophy that if a starter goes down with injury, the next man up will do just as good a job.

That philosophy was put to the ultimate test Sunday, as the Colts were without the services of defenders Tyjuan Hagler, Marlin Jackson and 2007 NFL Defensive Player of the Year Bob Sanders.

The trio was placed on the injured reserve list during the week after suffering season-ending injuries.

With those players out, it just opened up the possibility for others — Melvin Bullitt and Jerraud Powers in particular — to make their impression felt.

And what an impression they made, as Powers finished with 10 tackles and an interception, while Bullitt added seven tackles to help lead the Colts defense in their 20-17 victory over the Houston Texans.

“We’ve been having some guys out all year, and we have two rookie cornerbacks,” Bullitt said. “Losing Bob is always a big blow, but someone has to step up.”

That defense shined early, limiting Houston to just a 56-yard field goal as time expired in the first half. That 13-3 halftime advantage could have been much smaller, however, if it weren’t for Powers.

“We’ve been screaming since (the preseason) a next-man-up philosophy around here,” Powers said. “We looked at it as an opportunity. It was unfortunate we had a lot of guys go out this week, but the next guy up is a big opportunity for us and we just wanted to step up to the challenge and make some plays.”

With the clock coming up against the 2:00 warning, Houston’s Ryan Moats fumbled the ball near the Colts’ end zone.

Alertly noting that Antoine Bethea had knocked the ball loose, Powers leapt back onto the field to corral the loose ball, keeping the Texans from scoring and giving the ball back to the offense.

“I just knew I had to get back in bounds,” Powers said. “Antoine made a heck of a play.”

Though the Texans rallied for two second-half touchdowns to take a 17-13 lead into the fourth quarter, that defense was called upon to come up with one final stop to preserve the victory.

Houston would move down the field to set up a potential game-tying field goal in the final seconds.

Next man up — even on special teams.