How do you knock out a heavyweight champion?

Well, for starters, you better have a good jab working.

And a lot of patience.

Credit the Colorado coaching staff for sticking with the running game Saturday afternoon after falling behind No. 3 Oklahoma 24-7.

In the game, Hugh Charles had 13 carries that went for 2 yards or less, including six that went for negative yardage. Demetrius Sumler had seven carries that went for 2 yards or less, including three that went for no gain.

And Byron Ellis, despite averaging 5.8 yards a touch, added a 2-yard carry in the cloud of dust that was Folsom Field.

By late in the third quarter, it was all adding up to some big plays for the Buffs on the ground, which paved the way for the 27-24 upset of the Sooners.

"It does serve a purpose," Ellis said of the series of short runs. "We feel they had a good run defense but if you keep going at them, like any other defense, they're going to have to wear down eventually. And then those 1- and 2-yard gains start turning into 5 and 6. Then you start breaking those 5- and 6-yard gains into the 20-plus."

Like Charles' 25-yard touchdown run with 8:26 remaining in the second quarter, which tied the score 7-7.

OU's Allen Patrick responded with a couple of impressive counterpunches — touchdown runs of 34 and 17 yards — to give the visitors a 17-point lead in the third quarter.

But instead of abandoning the script and putting the comeback entirely on Cody Hawkins' shoulder pads, CU head coach Dan Hawkins and offensive coordinator Mark Helfrich marched on with the smashmouth strategy.

"That's just a trust factor between Coach Hawk and the running backs," Charles said. "He trusted us. He knew we were going to get it done and he allowed us the opportunities."

After an interception by safety Ryan Walters, CU found itself back in the game. Ellis ran for 5 yards on first down, then Charles broke a 10-yard run, Ellis a 12-yard run, and Charles a 23-yard run.

The nine-play, 62-yard drive was capped with a 4-yard touchdown pass to Tyson DeVree, which was set up by the play-action and included a sack-saving block by Ellis to cut the deficit to 24-17 with 14:50 remaining.

"I do think we wore on them just a little bit," Dan Hawkins said. "Probably a little bit more than they thought was going to happen, given what we've done up to this point. But you keep chipping away, you've got the right mentality, you don't get disturbed by a no-gain or a 2-yard gain, and you keep coming back."

Charles finished with 110 yards on 24 carries (4.6 per). Sumler had 37 yards on 13 carries (2.8 per). And Ellis added 29 yards on five carries.

The crestfallen Sooners crept off the field in disbelief after Kevin Eberhart's game-winning field goal at the gun.

This one must have felt like a low blow for the OU faithful.

"We just put our pad levels a little lower and started driving," Buffs true freshman left guard Kai Maiava said of his unit's second-half execution.