Xavier Johnson fired in a game-high 32 points Tuesday night and Clarence Rupert converted a tiebreaking three-point play with 27.5 seconds left as Southern Illinois stopped Oklahoma State 70-68 in Carbondale, Ill.

Rupert, who finished with 13 points (11 in the second half), rebounded Johnson's miss and curled in a layup while being fouled by Brandon Garrison. The play added a touch of irony as the Salukis (6-2) won via a rebound on a night when the Cowboys controlled the glass 43-24.

Oklahoma State (3-5) got within a point after Javon Small made two foul shots with 17 seconds left after a technical foul on Troy D'Amico. The Cowboys could have taken the lead, but Small and Quion Williams missed a pair of mid-range looks in the closing seconds. Kennard Davis got the rebound off Williams' miss and made a foul shot with 0.5 seconds remaining to cap the scoring.

Johnson, who came into the game fourth in Division I in scoring at 23.1 points per game, was 9 of 22 from the field and 13 of 15 from the free-throw line. He also dished out five assists.

Small scored 25 points for Oklahoma State, which lost for the third time by one possession. Jarius Hicklen added 12 off the bench, all on 3-pointers.

Oklahoma State controlled the early portion of the game, using its length and quickness to stifle an offense that came in averaging 79.4 ppg. And it lured Johnson into two fouls in the first 3:21, forcing him to the bench for a brief spell.

But Johnson started utilizing his talent at drawing fouls and then making the free throws to enable Southern Illinois to erase its early seven-point deficit. He got to the line a whopping 13 times in the half, making 12 on his way to 19 points at intermission.

However, the Cowboys were able to even the game before halftime when they grabbed a pair of offensive rebounds off a missed one-and-one, eventually converting them into a driving layup by Bryce Thompson. That made it 34-34 at the break.

--Field Level Media