Oklahoma State's Ivan McFarland (23) shoots as Southern Illinois' Darren Brooks (1) plays defense in the first half of their NCAA tournament second-round game in Oklahoma City Sunday, March 20, 2005. (AP Photo/Sue Ogrocki)

OKLAHOMA CITY (AP) -- Ivan McFarlin swiped the ball, hurtled down the court, and crashed to the hardwood -- then got up with a smile. He was having the game of his career.

With leading scorer Joey Graham seated on the bench thanks to four fouls, McFarlin powered a 10-2 run that extended Oklahoma State's lead, and the Cowboys beat seventh-seeded Southern Illinois 85-77 Sunday in the second round of the NCAA tournament.

McFarlin scored a career-high 31 points, and his sequence during the run was tremendous. He first scored on a reverse layup from a pass by Terrence Crawford, then returned the favor with a pass to set up Crawford's right-handed jam.

After Stetson Hairston answered with a driving layup for Southern Illinois, John Lucas III hit a jumper in the lane before McFarlin added a pair of layups under the basket against LaMar Owen.

He went stumbling downcourt after a steal on the Salukis' next possession and got up smiling after he and Matt Shaw got tangled up, then slapped a high five to JamesOn Curry before heading to the bench for a timeout. His two ensuing free throws gave Oklahoma State a 68-57 lead -- its largest of the game.

The Salukis (27-8) got back within 72-68 on a 3-pointer by Jamaal Tatum, but Curry called for the ball and answered with a 3-pointer of his own. The second-seeded Cowboys (26-6) hit all eight of their free throws down the stretch and McFarlin added a two-handed jam with 44.3 seconds left to keep his team ahead.

Oklahoma State coach Eddie Sutton called McFarlin out of the game with 14.9 seconds left, and gave him a hug before he allowed the fifth-year senior to sit down. Athletic director Harry Birdwell also gave McFarlin a bear hug while a crowd clad in orange stood to applaud.

With the win, Oklahoma State advances to play in the round of 16 in consecutive seasons for the first time since 1991-92. The Cowboys will play third-seeded Arizona (29-6) next weekend in the Chicago Regional in a meeting of the two oldest coaches in the tournament. Arizona's Lute Olson is 70, and Sutton is 69.

McFarlin, the Cowboys' interior workhorse, thrives in the NCAA tournament, averaging 11.8 points and 9.5 rebounds in nine previous games. His teammates call him ``The Warrior'' for his blue-collar attitude on the court that's completely the opposite from his lighthearted, jovial demeanor off of it.

Southern Illinois coach Chris Lowery called McFarlin the ``heart and soul'' of the Cowboys after he scored 18 to lead them in a first-round win against Southeastern Louisiana.

Curry added 18 and Lucas had 17 as the Cowboys rallied in the second half.

After trailing by seven, the Cowboys stormed out of halftime with 12 consecutive points to take a 51-46 lead. The Salukis came back to go up 52-51, but McFarlin's two free throws with 14:06 left gave the Cowboys the lead for good.

Tatum finished with 22 points to lead the Salukis.