Gophers coach P. J. Fleck watched from the sideline during the first half at Northwestern on Saturday night. (Erin Hooley, Associated Press/The Minnesota Star Tribune)

EVANSTON, ILL. – Last week, P.J. Fleck wore the look of disappointment after his Gophers made too many mistakes in what he considered a winnable game at North Carolina.

Saturday night at Ryan Field, Fleck wore the look of utter frustration because the Gophers not only blew a 21-point fourth-quarter lead over Northwestern and lost 37-34 in overtime, but they collapsed while his old reliable formula failed.

"We called the game, especially going into the fourth quarter, relying on what we rely on,'' Fleck said. "Unfortunately, that came back to bite us tonight. Playing really good defense, flipping field position, making [opponents] go long fields. … It's what we do well and what we rely on 99% of the time.''

Turns out, Northwestern had that other 1% in its back pocket.

Fleck got his coaching start as a graduate assistant at Ohio State under Jim Tressel and learned a strategy that came to be known as "Tressel-ball.'' By combining a stout defense that gives up few big plays, solid special teams and an offense that uses a clock-munching, mistake-avoiding ground game, Tressel guided the Buckeyes to the 2002 national championship.

The formula has served Fleck well at Minnesota. With the Gophers, he has an 11-win season and two nine-win campaigns. Through the better part of three quarters Saturday, it was working for the Gophers, who led 31-10 when Darius Taylor powered through a would-be Wildcats tackler and sprinted 43 yards on a fourth-down carry for a touchdown and 21-point lead. That came with 2:11 left in the third quarter, seemingly the dagger delivered by the Gophers.

The Wildcats started their rally with an 11-play, 75-yard drive capped by Cam Porter's 1-yard TD run that made it 31-17 with 12:01 left in regulation.

Tressel-ball breaks down when offenses can't sustain drives and defenses give up big plays and can't make stops. That's what happened to the Gophers in the fourth quarter.

Minnesota's offense followed Porter's score with a three-and-out on two runs and an incomplete pass. Three plays and only 39 seconds following a Gophers punt, the Wildcats were within 31-24 as wide receiver Bryce Kirtz burned the Minnesota defense for gains of 21, 31 and 17 yards for a touchdown with 9:46 remaining.

After the teams traded punts, Minnesota got the ball with 4:49 left. Athan Kaliakmanis' 19-yard option keeper gained a first down, but the Gophers couldn't get another when Taylor was stopped for a 1-yard loss on third-and-2 from the Wildcats 36. Fleck opted to punt.

"If we get another first down,'' Fleck said, "the game's over.''

Instead, Northwestern took over at its 20 with 2:07 left, drove 80 yards and got the tying touchdown on Ben Bryant's 11-yard TD pass to A.J. Henning with two seconds to play. In overtime, the Gophers opened with a 20-yard field goal by Dragan Kesich before the Wildcats played the trump card with Bryant's 25-yard TD pass to tight end Charlie Mangieri.

Fleck took stock of things afterward and sounded as if he might be questioning his approach.

"You always look at yourself first as a head coach,'' he said. "What could you have done differently? What could you have done better?''

There clearly was an emphasis on the passing game in the first half, when Kaliakmanis completed all eight of his passes for 97 yards and two TDs. In the fourth quarter, though, the Gophers ran the ball 11 times and passed it three times.

The Gophers' defensive play in the fourth quarter torpedoed the old reliable strategy. They gave up 169 yards, 11 first downs and allowed the Wildcats to convert five of six third-down situations.

Last week, North Carolina star QB Drake Maye worked over the Gophers defense for 414 passing yards. This time, Bryant, a less-heralded QB transfer from Cincinnati, roasted the Gophers for 396 yards and four TDs.

"Anything that could have gone wrong, went wrong in that fourth quarter,'' Fleck said.