Source: Colt McCoy will start Sunday

Although it's not a surprise, it is now official: Rookie quarterback Colt McCoy will make his NFL debut Sunday for the Cleveland Browns.

After two days of practices and with two veteran quarterbacks still ailing, McCoy is "definitely" starting against the Pittsburgh Steelers (3-1), a source told ESPN.com Thursday evening. Barring something "extremely unforeseen" those plans won't change, the source said.

Browns head coach Eric Mangini told the media this week that he's "leaning" in that direction but has yet to publicly announce McCoy as the starter. But behind closed doors, the Browns (1-4) informed the rookie third-round pick as early as Monday to get ready to play, because the team didn't anticipate quarterbacks Jake Delhomme and Seneca Wallace to return from severe ankle sprains. Both veterans missed practice Wednesday and Thursday while McCoy took the first-team reps.

A third-round pick from the University of Texas, McCoy will face a Pittsburgh defense that is ranked No. 4 in the NFL. McCoy is the winningest quarterback in college football history and is known for his accuracy. He went 13-for-13 in his final preseason game for the Browns.

James Walker covers the AFC North for ESPN.com