INDIANAPOLIS -- In a defense-dominated league, it's backbreaking to be so dependent on an offense to win games every Sunday. Ask the St. Louis Rams. Mike Martz tried that last year, bowed out in the first round of the playoffs to New Orleans and replaced eight starters during the offseason.

The Indianapolis Colts couldn't take that plunge because of the salary cap and now they are paying a heavy price. General manager Bill Polian and coach Jim Mora tried patching up the league's 11th-worst defense last season. They tried with bargain signings such as Christian Peter, Mike Wells, Thomas Smith and Mike Morton and rookie safeties Idrees Bashir and Cory Bird.

	Miami's Travis Minor, left, outruns the Colts' David Macklin (27) and Idrees Bashir for a 56-yard touchdown.

Never was this more evident than the Colts' demoralizing 27-24 loss to the Miami Dolphins, their third consecutive home loss. Great divisional games go down to inches and half steps. For example, Dolphins cornerback Patrick Surtain grabs the back of Marvin Harrison's jersey on a 50-yard toss from Peyton Manning that keeps Harrison a half step from making the game-winning catch with 5:30 left in the fourth quarter.

A series earlier, Manning gets hit in the jaw on a helmet hit by Dolphins defensive end Lorenzo Bromell and has to rush to the sidelines to stop the bleeding. Enter backup Mark Rypien, who audibles to a Dominic Rhodes run that turns into a fumble on a great diving reach by linebacker Derrick Rodgers. That was the first time in Manning's career he's missed a snap because of an injury. What happens in his absense? The Colts fumble, and there is a possibility that Manning might have to miss next week because of a fractured jaw.

Count these close plays that happened on defense. Dolphins rookie halfback Travis Minor takes a handoff around right end and breaks down the sidelines for a 56-yard touchdown. Colts defenders either took bad angles or didn't tackle Minor when they had the chance. Out of a four-receiver set in the second quarter, rookie receiver Chris Chambers beats Thomas Smith on one-on-one coverage for a 75-yard touchdown as if he were jogging alone.

Chambers' game-winning 29-yard touchdown came when safety Chad Cota didn't realized he was playing two-deep zone so Chambers went untouched into the end zone. That's three plays and three touchdowns for 159 yards with plenty of room to spare where the offensive players aren't at least contested on every play.

That's not going to get you to the playoffs, and it's the reason the Colts are 4-4 and about ready to have the horseshoe removed from their hoof as a playoff contender.

"I'll tell you one thing. I can't fault the effort of our football team," Colts coach Jim Mora said. "I don't think we can play any harder. We played about as hard as we can play. We just came up a little bit short."

No doubt. Mora's offense had to spend 61 plays trying to keep up with what the Colts' defense gave up in three plays. The Colts are giving up 28 points a game while scoring 28. From the looks of the Colts' training room after the game, you can figure the good times on offense are going to end.

Manning had to visit a dentist Sunday night to determine if his jaw was fractured. Halfback Edgerrin James, who has missed two games with a knee ligament injury, might be out another week or two. Rhodes, James' backup, had his shoulder pop out of its socket on the third play of the game. Though he returned to finish with a respectable 42 yards on 14 carries, Rhodes had to play wearing a shoulder harness and was worthless blocking against blitzing Dolphins defenders.

	“	It was an extremely disappointing loss. A little bit here and a little bit there and it could have been different. I don't know what to say. ”
		— Peyton Manning, Colts quarterback

On defense, the Colts lost their best defensive player, linebacker Mike Peterson, in the first half with a torn posterior cruciate ligament that will sideline him for a couple of weeks. Bird sprained a knee. Guard Steve McKinney suffered a small fracture in his back.

To make matters even more dismal, the Colts have a finishing schedule against teams with a combined record of 42-28, with seven of them contending for the playoffs. They might have to jump into that second half of the season without James, Manning and Peterson.

"I don't use injuries as an excuse ever," Mora said. "That is part of the game."

But Mora and the Colts have been embarking on new ground the past couple of weeks anyway. James never missed a practice or a game before he suffered his knee injury in the Oct. 25 victory over the Kansas City Chiefs. Manning has missed just 51 plays in his NFL career, but only one play because of injury -- that one-play fumble by Rypien in the fourth quarter.

In Indianapolis, though, it's all about the offense because it has to be. Opposing defenses know that and play at a frenzied level. For defenders, it's like basketball. Ask Surtain, who had the almost impossible job of covering Harrison.

Surtain knows from playing against Manning and Harrison that the defense will give up plays. But they also have a chance to make a few plays, too. In the second quarter, Manning tried a bomb to Harrison, who happened to be covered by Pro Bowler Sam Madison on the play. Madison grabbed the ball a half-second before Harrison and landed on his right shoulder, suffering a third-degree dislocation that might sideline him for a month.

Harrison wrestled the ball away and tried to get into the end zone, but officials ruled Madison had possession first. It was one of two interceptions thrown by Manning. That didn't stop Manning from working Harrison against Surtain. For the game, Harrison had nine catches for 174 yards and three touchdowns, two from the slot and one on the outside against Surtain.

Surtain stayed so focused that he made two key stops in the final minutes.

"I picked up on an audible call that Peyton made early in the game in which Marvin ran a particular route," Surtain said. "He came back and made the same audible, where Marvin ran a pump and go. He went by me, and I just slowed him down a little bit so I can get back on top of him. The ball was a little bit overthrown."

Surtain grabbed even more of Harrison's jersey with 2:21 left on a pass over the middle that he stopped. Manning tried to get the officials to throw a flag. They didn't. And for whatever reason -- maybe it was Manning shouting plays with a tight jaw -- offensive tackles Adam Meadows and Tarik Glenn each had costly false starts in the final drive that ended with a fourth-and-21 incompletion.

"It was an extremely disappointing loss. A little bit here and a little bit there and it could have been different," Manning said. "I don't know what to say. Bromell knocked the (stuff) out of me. My teeth and chin are pretty sore."

Expect Bromell to be fined by the league. Expect the Dolphins to pool their money in the locker room to cover Bromell's loss. That play and the three-point victory puts the Colts as a distant challenger for the AFC East behind a 6-3 Jets team. And there might be no Manning and no James in the future.

The only constant is that the Colts had no defense when they needed it.

John Clayton is a senior NFL writer for ESPN.com.