LAWRENCE, Kan. — Markel Brown let out a roar. Marcus Smart did a cart-wheel and a back flip.

Travis Ford exhaled for the first time all game.

After establishing a big first-half lead, Oklahoma State watched it all melt away Saturday. But in one of the rare instances of a team refusing to lose at intimidating Allen Fieldhouse, Brown and Smart managed to hold things together down the stretch against second-ranked Kansas.

Together, they helped the Cowboys pull out an 85-80 victory that ended the Jayhawks’ nation-leading 18-game winning streak — and their 33-game streak at the Phog, too.

“We just beat one of the top teams in the country, and a great team at that,” said Smart, who had seven of his 25 points in the closing minutes. “It’s hard for teams to come into their home court and get a victory. We’re one of the few teams that have done it. We couldn’t believe it.”

That may account for his impromptu gymnastics.

“I was so ecstatic about the victory,” the freshman said, “it just came to me to do it.”

Brown finished with 28 points for the Cowboys (15-5, 5-3 Big 12), who hadn’t beaten a top-5 team on the road since knocking off the Jayhawks on Jan. 2, 1958.

Oklahoma State stunned the Jayhawks by building a 14-point lead in the first half, but Kansas had pulled ahead 64-60 on a 3-pointer by Naadir Tharpe midway through the second half.

The Jayhawks still led by six when Phil Forte hit a 3-pointer from the wing with 4:15 left to begin a 13-2 charge, allowing Oklahoma State to seize control.

The Cowboys’ stretched the lead to 77-69 with 50 seconds remaining, but the Jayhawks (19-2, 7-1) managed to play savvy defense and take advantage of a couple missed free throws. Andrew White III’s 3-pointer made it 78-75, and his free throw made it 78-76 with 36 seconds left in the game.

Forte, an 89-percent foul shooter, made two at the line to restore a cushion, and White answered with two of his own. Smart added a free throw, and Johnson’s layup cut the Cowboys’ lead to 81-80.

Forte calmly made two more free throws with 7.9 seconds remaining, and Johnson turned the ball over near mid-court before Kansas could even get up a tying 3-point attempt. Forte got ahold of the ball and laid it in at the buzzer to punctuate the victory.

“This place here, it’s one of the greatest environments in college basketball, against a great basketball team,” said Ford, who had been 1-5 in his coaching career against Kansas. “We figured a way out to score a few points. Really proud of our effort.”

Forte finished with 11 points for the Cowboys, all of them in the second half.

Ben McLemore had 23 points to lead Kansas. Kevin Young added 12 and Jeff Withey had 10 as the Jayhawks lost at home to Oklahoma State for the first time since Feb. 8, 1989.

Johnson’s turnover in the closing seconds was the 16th of the game for the sloppy Jayhawks. They also had 16 earlier in the week, when they struggled to get past West Virginia.

“We don’t have a guard,” Self said despondently. “We don’t have a point guard.”

Having one sure would have helped in the first half.

That’s when the Cowboys took control with a 19-3 run, taking advantage of the Jayhawks’ lousy offense while getting the ball in the hands of Brown, who had 11 points during the surge.

“We had to come out, punch them in the mouth and not let the crowd get into it,” Brown said.

By the time Brown was fouled by Johnson and converted the three-point play with 10:58 left in the half, Oklahoma State had a 26-12 lead — the largest by anybody against the Jayhawks all season.

Kansas eventually went on an 11-3 run of its own to get back into the game, but Brown delivered another 3-pointer out of a timeout and Oklahoma State managed to maintain a 40-34 lead at the break.

Brown finished the first half with 22 points, just two off his season high. The junior guard was 7 of 10 from the field, 5 of 7 from the arc and even had a couple assists.

Brown hit another 3 out of halftime before Kansas finally started to execute.

McLemore led the way with 11 points during a 16-4, momentum-changing run. Twice he finished off alley-oops from Johnson, and his lay-in with 13:23 left gave Kansas a 50-47 lead.

Smart and Brown refused to let the Cowboys wilt, though.

Smart, who considered Kansas before signing with the Cowboys, scored back-to-back baskets, and Forte finally scored after missing his first eight field-goal attempts. Brown then hit his seventh 3-pointer, pulling Oklahoma State within 59-58 with just over 8 minutes left in the game.

Forte added his first 3 moments later, and Michael Cobbins followed up a miss by Forte with a massive dunk that allowed the Cowboys to regain a 67-66 lead with 3:45 remaining.

“They got the best of us, definitely, on offensive rebounds,” Withey said.

Le’Bryan Nash, who had struggled all game, beat the shot clock with a jumper with 2:40 left that gave Oklahoma State a 69-68 lead. And despite some tense moments down the stretch, they did enough on defense and at the foul line to hang on for a signature victory.