HOUSTON (AP) -- The No. 13 Oklahoma State Cowboys have been known more for their offense than their defense.
The Cowboys' defense, however, kept Oklahoma State in the game long enough for their offense to wake up Saturday against the Mississippi State Bulldogs.
J.W. Walsh threw for 135 yards and ran for another 125 and a touchdown to lead Oklahoma State to a 21-3 win over Mississippi State in the Texas Kickoff.
Walsh finished 18 of 27 after relieving starter Clint Chelf on the Cowboys' third series.
Oklahoma State head coach Mike Gundy said Walsh would be the starter at UT-San Antonio next week.
''It was exciting to get in the first game of the year that we have been waiting all year for,'' Walsh said. ''It was a lot of fun and exciting. There were some tough moments at the beginning, but once we got in our stride, we were good.''
Jeremy Smith rushed for 102 yards and two touchdowns on 15 carries for Oklahoma State (1-0), which piled up 432 yards on offense after struggling for most of the first half.
''We wanted to be more physical than they were in the running game,'' Gundy said. ''Early, we were very poor at that, but as the game wore on, we felt like we became more physical than they were on both sides of the ball running it and defending the run, so we stayed with that and allowed J.W to stay with that when he came in. He gave us a little bit of a spark.''
Tyler Russell finished 10 of 16 for 133 yards before being helped off the field and taken to the locker room in the third quarter after being brought down on a scramble. Dak Prescott replaced Russell, throwing for 89 yards on seven of 17 passing.
Mississippi State head coach Dan Mullen would not specify what injury Russell had, but said the quarterback would be looked at again.
''Overall, he is going to be OK,'' Mullen said. ''Anytime you have a head or neck injury, you're going to take every precaution, and I know he is going to get it looked at again.''
LaDarius Perkins rushed for 50 yards on 16 carries and caught three passes for 52 yards for the Bulldogs (0-1), which had only 333 yards of offense and had trouble keeping drives going, finishing two of 16 on third down conversions.
''We were 2 for 16 (on third downs); that's terrible,'' Mullen said. ''And those were momentum killers early on. We missed some short ones early on, and even though we controlled the tempo for the most part, we just could not get anything going.''
Oklahoma State's defense also had three sacks and intercepted two Mississippi State passes.
''We had guys flying to the ball,'' Oklahoma State cornerback Justin Gilbert said. ''We were making substitutions with our defensive line on and off the making. We were moving around. Our guys were just making plays.''
Gundy gave the defense credit for keeping the Cowboys in the game.
''We were bad on offense the first 20 minutes of the game,'' Gundy said. ''Our defense kept us in it. If the defense doesn't play well and challenge Mississippi State with stops and gets an interception, we are playing catch up.''
Oklahoma State's offense gained only 67 yards with less than four minutes remaining in the first half before Walsh got going.
Walsh worked the quarterback keeper three times for gains of 46 yards down the left sideline, 12 yards down the left sideline to the MSU 3 and capping it off with a 3-yard touchdown run to give the Cowboys a 7-3 lead with 2:16 left in the half.
''We started really slow,'' Gundy said. ''The defense kept us in the game. The offense couldn't get any rhythm. We had dropped passes and penalties. Our success on offense is based on running the ball, play pass, throwing it, mixing it up, changing direction. When you have penalties and dropping the football, it is tough for us to have success.''
OSU continued the offensive momentum in the second half, driving 75 yards in 11 plays to take a 14-3 lead on a Smith 1-yard run with 10:41 left in the third.
Smith tacked on a 20-yard touchdown run to begin the fourth quarter to up the lead to 21-3.
The Bulldogs looked to respond before the half as Jameon Lewis weaved the kickoff return 66 yards to the OSU 34, but a holding penalty and a sack by Tyler Johnson stopped the drive.
Mississippi State marched down the field in 57 yards on 13 plays taking over six minutes off the clock, but the Bulldogs were only able to get Devon Bell's 40-yard field goal to take a 3-0 lead. Russell was 5 of 7 on the drive for 58 yards.
''I think we just need to get better at the small things,'' Lewis said. ''Our offense needs to get better, and we need to work harder.''