PHILADELPHIA -- Donovan McNabb took the Philadelphia Eagles to first place in the NFC East. Koy Detmer will have to keep them there.

McNabb probably will miss the rest of the regular season and could be out for the playoffs because of his broken right ankle. Detmer, who hasn't started a game since 1999, takes over for the two-time Pro Bowl quarterback.

"I'm looking at it like Donovan is going to take care of business and do what needs to be done and that we don't have Donovan for the season and we move on,'' Eagles coach Andy Reid said Monday. "I think it's important that the football team functions that way. We have full trust in what Koy's going to do.''

McNabb was injured on the third play of Sunday's game against Arizona, but he stayed in and threw a career-best four touchdown passes to lead the Eagles past the Cardinals 38-14.

The Eagles (7-3) have six games left and hold a one-game lead over the New York Giants in the division. McNabb could possibly return for the playoffs, but Reid said it's too early to set a definite timetable.

McNabb, his family and the Eagles' medical staff are considering options that include surgery or letting the broken bone heal on its own. It's possible McNabb could return sooner if he had surgery, but that hasn't been determined.

"We'll have a better idea in the next day or so,'' Reid said. "We're looking at right now six-to-eight weeks.''

Sources told ESPN that Eagles quarterback Donovan McNabb flew to Houston on Tuesday with his agent, Fletcher Smith, to see an orthopedic specialist for a second opinion. No decision has been made regarding surgery.

McNabb, who has never had a serious injury, had insisted he'd try to play against San Francisco next Monday night. He has made 53 straight starts, including playoffs.

But his streak will end when Detmer takes the snaps against the 49ers (7-3) in a game that has significant playoff implications.

Detmer, a seventh-round pick by the Eagles in 1997, was 1-4 as a starter in 1998 for a team that finished 3-13. He won his only start in 1999 when the Eagles went 5-11. He has completed 113 of 227 passes (49.7 percent) for 1,240 yards, eight TDs and nine interceptions in six seasons, and has thrown just 17 passes since his last start.

"It's a huge difference,'' Detmer said about starting. "Now you're the guy out there trying to make things happen.''

A.J. Feeley will back up Detmer, and the Eagles are looking for a No. 3 quarterback.

McNabb went down after he was sacked by Adrian Wilson and LeVar Woods on third-and-4 on the opening possession. He clutched his right leg and stayed on the turf after losing the ball, but returned on Philadelphia's next series.

X-rays after the game showed the break in his fibula.

McNabb insisted he was fine during the game so no X-rays were taken at halftime. Reid said McNabb didn't further damage his ankle by playing on it.

"Between Donovan's description and the examination of the medical staff, all signs pointed toward a normal ankle sprain,'' Reid said.

Unable to scramble because of his injury, McNabb stayed in the pocket and threw TD passes of 2 yards to James Thrash, 3 to Dorsey Levens, 27 to Todd Pinkston and 9 to Duce Staley in the first half.

Though he limped noticeably the entire game, McNabb didn't miss a play until coming out with 4:49 left. He finished 20-of-25 for 255 yards and one interception, but he had no rushing attempts for the first time in his career.

"On the sideline, he was smiling, joking,'' Reid said. "He must have a tremendous pain threshold. I can just imagine. He's a unique character.''

McNabb, the No. 2 overall pick in the 1999 draft, got off to the best start of his career in his fourth year in the West Coast offense. He completed 68 of 111 passes (61.3 percent) for 791 yards, eight TDs and two interceptions in the first three games. He also ran for 118 yards and two TDs.

Before his outstanding performance against Arizona, he was 123-for-225 (54.6 percent) for 1,243 yards, five TDs, three interceptions and had 342 yards rushing and four TDs on the ground in the previous six games.

"I'm as heartbroken as anybody to watch Donovan go down,'' Detmer said. "He's a great guy and a great player.''