NORMAN, Oklahoma (Ticker) -- After a first half of futility, seventh-ranked Oklahoma State figured out the defense of its archrival.

Ivan McFarlin scored 14 of his 21 points in the second half and Joey Graham sparked a key run as the Cowboys pulled away for their 10th straight win, a 65-52 Big 12 Conference triumph over Oklahoma.

Oklahoma State looked like it was in trouble after scoring a season-low 26 points in the first half. But the Cowboys trailed by just one at the break and seemed to solve their offensive woes in the locker room.

John Lucas opened the second half with a 3-pointer to spark a 14-4 run for Oklahoma State (20-2, 10-1 Big 12). Graham scored seven points during the spurt, completing a three-point play to give the Cowboys a 40-31 cushion with 14:52 left.

The Sooners struggled in the second half, going more than nine minutes without a basket until Jason Detrick made a layup with 9:35 left.

"The first four minutes of the second half were crucial," Oklahoma coach Kelvin Sampson said. "We had some shots that were great shots but didn't go in."

Oklahoma (16-5, 6-4) climbed within 44-40 with just under nine minutes left, but Oklahoma State scored 17 of the next 21 points to put away the game, highlighted by seven from McFarlin.

"In the second half, I just wanted to come out hard. I did not want to let my teammates down," McFarlin said. "My shots were just falling at the right time. I knew we needed a spark and I provided that."

Lucas also scored seven points during the stretch, starting it with a 3-pointer and capping it with a pair of free throws for a 61-44 edge with 3:10 remaining.

Oklahoma State matched its first-half total less than 14 minutes into the second half. It made 15-of-24 shots and 7-of-9 free throws in the final 20 minutes and swept the season series.

"In the second half, we played much better," Cowboys coach Eddie Sutton said. "It was a good win. You don't sweep these guys too often."

"We weren't tough enough defensively in the second half," Sampson said. "That's a toughness issue right there. My hat is off to Oklahoma State."

McFarlin made 10-of-12 shots from the floor and Graham had 13 points on 6-of-8 shooting as the Cowboys finished at 55 percent (26-of-47).

Lucas totaled 18 points for Oklahoma State, which scored 40 in the paint and held a 36-28 rebounding edge.

Jabahri Brown scored 16 points and Detrick and De'Angelo Alexander had 11 apiece for the Sooners, who shot just 31 percent (17-of-55), including 4-of-19 from 3-point range.

"We just played bad," Brown said. "Our shots were not falling and our defense was very poor. We never could get a stop when we needed it."