BEREA, Ohio (AP) -Derek Anderson passed his first NFL assignment. His next one could be a lot tougher.

Anderson, who replaced injured Browns quarterback Charlie Frye on Sunday and rallied the Browns to an overtime win against Kansas City, may have to make his first pro start on Thursday against the blitz-happy Pittsburgh Steelers.

Frye hurt his right wrist early in the first quarter against the Chiefs. Initial X-rays taken at Browns Stadium were negative, but Frye, who sat out the second half, underwent an MRI exam at the Cleveland Clinic on Monday.

The club was awaiting those results on their tough second-year QB, who left the stadium wearing a brace following Sunday's game.

``We want to make sure there is nothing else there,'' Browns coach Romeo Crennel said. ``As soon as we find out something, we'll let you know what it is.''

Crennel also disputed a comment made by tight end Kellen Winslow, who after the game said Frye's wrist was fractured.

``It's not true to my knowledge,'' Crennel said. ``It's a little too early to make that determination. I have to see if he (Frye) can take the snap and how he throws during the week. After I see that, then I can make a determination.''

Crennel isn't ready to dismiss the possibility of Frye suiting up.

``I'm not ruling anything out,'' he said. ``Charlie's a tough guy. If he can take a snap and throw the ball, he'll want to go. It will depend on how much pain he can endure and how effectively he can throw the ball. I think that's what it will come down to.''

Even if Frye's wrist isn't broken, it's unlikely the Browns would risk putting him back on the field so quickly against the Steelers (5-7), who overcame a 10-point deficit in the fourth quarter to beat the Browns 24-20 on Nov. 19.

Frye has taken a pounding in his first full season as a starter. Cleveland's offensive line, missing two key starters because of injuries, has not done an adequate job of protecting Frye, who was having one of his best games - 11-for-13 for 122 yards and one TD - against the Chiefs before getting hurt.

Cleveland's front will have to do more to preserve Anderson, who will be subjected to Pittsburgh's relentless rush and multiple blitzing schemes. The Steelers bring pressure from every angle no matter who is under center and Anderson has be ready for it.

``He'll see the Pittsburgh-style defense and they are a blitz-zone team,'' Crennel said. ``They are not going to change that because of who the quarterback is. They might do more of it considering who the quarterback is.''

Although he had never thrown a regular-season pass until Sunday, the cannon-armed Anderson showed remarkable poise and precision while rallying the Browns (4-8). He finished 12-of-21 for 171 yards with two TDs - both to tight end Steve Heiden - and one interception. But Anderson made his biggest play with his size 17 feet, the same shoe size he's had since he was a 10-year-old growing like a weed.

In OT, he scrambled from trouble and rumbled down the right sideline for 33 yards to set up Phil Dawson's game-winning field goal. On the run, Anderson showed composure and confidence, something he has displayed in exhibition games and running the scout team in practice but had never had the opportunity to show on Sundays.

``This Derek Anderson guy,'' Crennel said, slightly shaking his head and smiling. ``I don't know where he came from.''

The Browns signed the former Oregon State QB off waivers before the 2005 season, one day after he was released by the Baltimore Ravens. Because they had committed to developing Frye this season, Anderson had been limited to one snap on Oct. 22 against Denver.

``You have a guy that you feel reasonably sure can do something in the game,'' Crennel said. ``Really, up until yesterday, we didn't know. We knew we had a young quarterback with a strong arm, but we didn't know how he would perform in the game. For him to go in and perform the way he did and lead the team to victory, now you feel confident about going into another game and playing at a high level.''

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