NORMAN, Okla. (AP) -- The three best quarterbacks Oklahoma has faced so far -- TCU's Trevone Boykin, Baylor's Seth Russell and Oklahoma State's Mason Rudolph -- were injured when their teams played high-stakes games against the Sooners.

Without the experience of dealing with those elite quarterbacks, Oklahoma will face its toughest test -- Clemson's first-team All-American and Heisman finalist, Deshaun Watson -- in a national semifinal on Thursday.

Russell sat out with a neck injury, and Oklahoma beat Baylor 44-34. Boykin missed the game against the Sooners with an injured right ankle, and Oklahoma escaped with a 30-29 win. Rudolph had a foot injury, and he played briefly in Oklahoma's 58-23 victory.

More from FoxSports

Oklahoma's defensive players say some practice time against their own quarterback, second-team All-American Baker Mayfield, has them prepared. The Sooners put Mayfield in some non-contact situations against the No. 1 defense before they took off for the Orange Bowl.

"We're going against, in my eyes, the best player in the country, Baker Mayfield," Charles Tapper, Oklahoma's All-Big 12 defensive end, said. "These live practices have been great for us because he's been scrambling around, trying to make plays, and we have to tag off on him to make sure we get him down."

Watson throws as well as anyone in the nation, but he also ran for 887 yards and 11 touchdowns this season.

"He's a great quarterback," Eric Striker, Oklahoma's second-team All-America linebacker, said. "I mean, everything about their offense, he is. As far as running, you've got to account for him in every way. It's going to be a great challenge defensively trying to slow him down or stop him.

"That guy right there, he's for real."

Oklahoma defensive coordinator Mike Stoops said Watson is much like Boykin, who passed for 318 yards and two touchdowns and ran 22 times for 77 yards two years ago in a TCU victory. Tapper said the Sooners have to make the most of their opportunities when they get to Watson.

"You make him play off you, we're not playing off him," Tapper said. "I'm making him react. He has to react off me. I'm rushing him, so if I get to him, I'm going to try to apply as much pain as I can so every time I'm hitting him, he's going to say, `I need to try to scramble out and I need to try to either throw the ball out of bounds to get away from all these big guys up front.' We're going to make him react off us."

Clemson beat Oklahoma 40-6 in the Russell Athletic Bowl last year, but Watson didn't play. Adding him to the mix makes the Tigers much more dangerous.

"You've just got to study, and you've got to make some good calls at the right time and try to put some indecision in the quarterback's mind," Stoops said. "And that's difficult because they're very well coached, and he knows where to go with the football and he knows when to run, so it's a very complete offense."

The Sooners played some dual threat quarterbacks this season and had success against them. The Sooners forced West Virginia's Skyler Howard into five turnovers and sacked him seven times in a 44-24 win. Kansas State's Joe Hubener ran for more than 600 yards this season, but he had just 16 yards on nine carries against Oklahoma, and the Sooners rolled 55-0.

Texas Tech's Patrick Mahomes had 47 yards on 15 carries, but the nation's current No. 3 passer in yards per game was held to 233 yards and threw four interceptions in Oklahoma's 63-27 win. Oklahoma State's J.W. Walsh, who filled in for Rudolph, had some success against the Sooners in the first half, but he was shut down in the second.

Tapper said there's an advantage to having played that kind of quarterback so many times.

"I feel like if we put a lot of pressure on him and get after him, it's like, most of the quarterbacks in the Big 12 play just like him, so we're used to the scrambling quarterbacks, the zone read, the read option," he said. "We've been going against this all season. Tennessee even did it so we're kind of used to it now."

Watson, though, is a tougher test.

MORE FROM FOX SPORTS SOUTHWEST:

- PHOTOS: Cowboys Cheerleaders Auditions

- Top 50 college football coaches salaries in 2015

- Most improbable bowl comebacks of the last 10 seasons

- Oldest player on every NBA team