On paper, everything looks perfect for Indianapolis.

The Colts are 10-0 again, in charge of the AFC South again, and could lock up another playoff spot in the next two weeks.

Yet with four straight victories by four points or fewer, coach Jim Caldwell knows this is not like the last time Indy opened the season with 10 straight wins. It's been a whole lot tougher.

"The realistic thing is that this is more typical of what you see week-to-week in the NFL," he said Monday. "I think there are a number of areas we need to improve upon, but the bottom line is we're getting the job done."

Nobody can quibble with the results. Indy holds a three-game lead in the chase for the AFC's top seed. What many want to know is whether the Colts might be living on borrowed time.

In some ways, this looks like the same old Colts.

They went 7-0 in 2007 before losing to eventual AFC champion New England. They were 9-0 before losing at Dallas in 2006, and they opened 13-0 in 2005 before San Diego finally stopped their quest for perfection. Peyton Manning has topped 3,000 yards for a 12th consecutive season, second only to Brett Favre's 17, and they have overcome the usual spate of injuries to key players.

In other ways, these Colts are very different.

Their 19-game regular-season winning streak is now the second-longest in league history, trailing only New England's 21-game streak. The Colts haven't missed a step with Caldwell taking over for Tony Dungy while Reggie Wayne and Dallas Clark have taken up the slack left by Marvin Harrison's departure. Wayne and Clark have combined for 141 receptions this year, the most by teammates over the first 10 games of a season in league history.

But the big change is how Indy is winning games.

Back in 2005, the Colts opened 13-0 with an average victory margin of 16.3 points. None of the wins came by fewer than seven points, though Indy wound up losing three of their last four including a divisional round game to eventual Super Bowl champion Pittsburgh.

This year, the Colts have won six of their 10 games by four or fewer points — including three straight escapes.

Houston's Kris Brown missed a potentially tying 42-yard field goal as time expired, Bill Belichick lost his risky fourth-down gamble and Baltimore's Joe Flacco threw an late interception, thwarting a chance at a possible go-ahead field goal Sunday.

Lucky? Perhaps.

Caldwell thinks all these close calls could make Indy a tougher playoff opponent.