STILLWATER, Okla. -- Oklahoma State's defense lost a key starter and gave up a touchdown midway through the third quarter.

Not the kind of start it needed to put away Arizona, who trails, 21-7.

Linebacker Alex Elkins suffered what looked like a left knee injury, and after being attended to for several minutes, was helped off the field.

That's a big loss for a young Oklahoma State linebacking corps, and Elkins already had a handful of tackles and a big hit so far in his night.

Arizona's drive was highlighted by a bit of razzle dazzle when the Wildcats caught the Cowboys on a well-executed hook-and-ladder from David Douglas to Keola Antolin to reach OSU territory.

Oklahoma State's offense has been stopped on four consecutive drives, and it needs to rediscover the momentum it had earlier in the game, or Arizona may sneak back into this game.