PHILADELPHIA (AP) - Donovan McNabb didn't practice yesterday because of a bruised chest, but the five-time Pro Bowl quarterback said he'll play in Philadelphia's home opener against San Francisco on Sunday.

"Nothing will stop me from being on that field," said McNabb, who was injured in the first quarter of the Eagles' 14-10 season-opening loss at Atlanta on Monday night.

If McNabb can't play - he's listed as questionable - longtime backup Koy Detmer isn't a lock to get the start. Detmer shared reps with third-string quarterback Mike McMahon in practice, and coach Andy Reid wouldn't select a potential starter.

"We'll see as the week goes on," Reid said. "I'll evaluate it and see what we want to do with it. I know both do a nice job."

Detmer has started eight games in his nine seasons with the Eagles. He led Philadelphia to a 38-17 victory in San Francisco in a Monday night game three years ago, one week after McNabb broke his ankle. Detmer threw for 227 yards and two touchdowns against the 49ers before injuring his elbow and missing the rest of the season.

McMahon started seven games in four seasons with Detroit before signing with the Eagles in the offseason. He isn't as familiar with Philadelphia's version of the West Coast offense, but he outperformed Detmer in the preseason.

"We're going to take the reps the way they want us to and see how it shakes out," said Detmer, who probably has maintained his status as the backup because he's the holder for Pro Bowl kicker David Akers.

Detmer expects to be on the sideline watching McNabb.

"He's a warrior," Detmer said. "We've seen him play through all kinds of things, broken ankles, everything. If he can walk, he can go. He will be out there."

McMahon said he's comfortable with the Eagles' complex offense.

"It's nothing too difficult," he said. "You just have to prepare and go out and help the offense move the ball. Don't do anything too fancy and move the chains."

McNabb didn't miss any plays after a crushing hit from Chad Lavalais sent him wincing to the sideline, but he struggled the rest of the game against the Falcons.

Coming off the best season of his career, McNabb threw one interception, lost two fumbles and often missed his target with erratic passes. He finished 24-of-45 for 257 yards and one touchdown.