CHAPEL HILL - When North Carolina point guard Ty Lawson limped off the court Sunday night, senior Quentin Thomas preferred to see it as a "challenge" rather than an "opportunity."

Whatever the wording, he'll likely face the biggest test of his college basketball career Wednesday night.

Although X-rays on Lawson's sprained left ankle were negative Monday, coach Roy Williams said "I don't think the chances are real good that Ty would play" when the third-ranked Tar Heels face No. 2 Duke on Wednesday.

The final decision won't be made until after today's practice at the earliest. (Lawson did not practice Monday.)

But the likely outcome leaves oft-injured Thomas -- whose various sprains, fractures and surgeries over the years have kept him from being a consistent force -- as the man who will need to fuel UNC's fast break, help defend the Blue Devils' perimeter scorers and feed the ball to All-America Tyler Hansbrough.

"It challenges me as a person, and it challenges us as a team,'' Thomas said after he stepped in for Lawson and scored a career-high nine points in a career-high 36 minutes in UNC's overtime win at Florida State. "I've been through ... a lot of ups, and a lot of downs. A lot of injuries, a whole bunch of stuff. ... I always tell myself: 'Be ready. No matter what happens, be ready.' "

He'll need to be.

While the Tar Heels (21-1, 6-1 ACC) were picked as the top team in the ACC -- and country -- in various preseason polls, Duke (19-1, 7-0) has been the better team of late, rolling over Virginia Tech, N.C. State and Miami while UNC squeaked by Georgia Tech and FSU and lost to Maryland.

A victory over Carolina on Wednesday would put the Devils two wins ahead in the ACC standings and in the driver's seat for the top seed in the ACC Tournament and the NCAA Regional in Charlotte.

Duke coach Mike Krzyzewski said he'll prepare his team as if Lawson were healthy.

"If he did not play, they would not change their style, and they have a senior point guard who would take his place,'' he said.

Which is why, UNC wing Marcus Ginyard said, there's "absolutely" no reason his team can't give Duke its first league loss of the season, even without its best ballhandler.

"Yeah, we're not going to be as fast on the break," said Ginyard, the starting small forward who will serve as backup point guard. "Without Ty, we won't be able to push the ball as fast, we won't be able to break down the defense as much. It's not that we can't do it without him, it's just that we'd be a lot more effective with him."

The biggest keys for Thomas against the Blue Devils: protecting the ball (Duke's opponents average 19.2 turnovers per game) and feeding it to Hansbrough (whom the guard-oriented Devils could have trouble stopping if he gets the ball in the lane).

The Tar Heels struggled to do those things after Lawson was hurt tangling with FSU's Ryan Reid for a loose ball.

"It was an adjustment for me, because with Ty's penetration ... Ty always finds me,'' said Hansbrough, who finished with 22 points and 21 rebounds but didn't score a field goal until mid-way in the second half. "It was a change, but Quentin stepped up."

Thomas accounted for only two of the turnovers, a far cry from the three he gave away in eight minutes at Clemson last month. That night, he was coming back from a two-game hiatus because of his own ankle injury.

"I'm a lot more controlled [now],'' Thomas said. "Coming back for that Clemson game, I was real eager to do a lot -- and at times too much. I made a mistake, and I wanted to do 10 times better the next play to disregard that mistake, and it kept building."

One thing on his side Wednesday: He has had success against the Blue Devils. As a sophomore in 2005-06, Thomas played two of the best games of his career against Duke. He got five points, four assists and no turnovers as he helped ignite a 17-point comeback before the Devils prevailed 87-83. Then he scored six points while helping UNC build an 11-point lead in an 83-76 upset of the nation's top-ranked team.

Granted, he came off the bench in those two games. Wednesday will be more of a "challenge."

"I want Tywon to be back,'' he said. "I'm not the type of player who thinks if someone on my team gets hurt, that's an opportunity for me. I always want our team to be full force, because we're a better team if we have everybody. But if need be, I just need to continue to step up."