Things looked even better after the Dolphins marched to a first-and-10 at the Steelers 49 and looked like they might put away Pittsburgh.
But after Ronnie Brown was stopped for a 2-yard loss on third-and-2 from the Steelers 41-yard line, it was one disaster after another.
The biggest blow, of course, was an 87-yard touchdown pass from Charlie Batch to tight end Heath Miller, the result of a badly blown assignment in the Dolphins defense.
Daunte Culpepper then threw an interception to Troy Polamalu, but the Dolphins caught a break when Jeff Reed badly missed a 44-yard field goal attempt.
So the Dolphins took over at their 34-yard line with a final chance to pull out a victory, but Culpepper was intercepted on first down by linebacker Joey Porter, who returned the pick 43 yards for a touchdown.
The Dolphins' last possession, for good measure, included two sacks and a holding penalty on tackle L.J. Shelton.
The Dolphins put themselves in position to win thanks to two Ronnie Brown touchdown runs and a big performance from Wes Welker, both as a receiver and returner.
The defense, however, had its problems with Batch, who stepped in for Ben Roethlisberger and threw three touchdown passes. The Dolphins also allowed Willie Parker to rush for more than 100 yards.
Offensively, the Dolphins got nothing going on the ground and eventually went almost exclusively to the passing game in the second half.
That was fine and dandy, until that game-turning third-and-2.
The Dolphins got a 37-yard punt return from Welker to set up their first touchdown and a 51-yard completion to Marty Booker after a short throw led to Brown's second TD run, which gave the Dolphins a 17-14 lead in the third quarter.
The way the game started, however, it didn't look like there would be much scoring at all.
The Dolphins managed only one first down on their first three drives, while they held Pittsburgh to three-and-outs the first two times the Steelers had the ball.
But the Steelers broke through on their third drive when they drove 75 yards between the first and second quarters to take a 7-0 lead.
The big play in the drive, culminated by Batch's 28-yard touchdown pass to Nate Washington, was a 4-yard run by Parker on fourth-and-1 from the Miami 39.
The Steelers gave the look of a run to the right before Parker went left and took a backhanded pitch from Batch away from the flow.
The Dolphins tied the game later in the second quarter thanks to Welker's 37-yard punt return, which gave them the ball at the Pittsburgh 15-yard line.
After a 12-yard pass from Culpepper to Brown, Brown ran up the middle for a 3-yard touchdown.
Pittsburgh took the lead right back with a 77-yard that was helped by a 24-yard pass-interference penalty on André Goodman on third down from the Miami 31.
The scoring play was a 7-yard pass from Batch to Hines Ward.
The Dolphins were able to get three points on the board before halftime, thanks again to the heroics of Welker.
After returning the ensuing kickoff 32 yards, Welker had catches of 29 and 20 yards to give the Dolphins a first-and-goal at the Pittsburgh.
The Dolphins could have had a touchdown, but Chris Chambers couldn't come up with a hard throw from Culpepper on first down.
Still, despite trailing 14-10 at the half, the Dolphins were in position to win the game. But they just couldn't make any plays down the stretch.