EDEN PRAIRIE, Minn. - Vikings coach Leslie Frazier could no longer ignore that Matt Cassel has been statistically the best of his three quarterbacks this season. So Frazier said Wednesday that Cassel would start Sunday's game against the Eagles at the Metrodome even though Christian Ponder, the starter for most of the season, is healthy again.

But after juggling quarterbacks all season, Frazier could have a new problem with his running backs.

With Adrian Peterson and Toby Gerhart battling injuries and not able to return to practice until Friday at the earliest, the Vikings (3-9-1) might have to turn to third-stringer Matt Asiata to handle the running. The second-year man has three career carries but none this season.

"The entire season, basically, we've had Adrian and Toby back there," Cassel said. "We'll just have to see come Sunday."

The Vikings have averaged 111.3 rushing yards in Cassel's three starts this season. In a 23-20 overtime win over Chicago on Dec. 1, when Ponder was knocked out with a concussion and Cassel took over late in the second quarter, Minnesota rolled up 246 yards rushing.

So, obviously, Cassel could find it more difficult against the Eagles without a productive back behind him. Peterson has rushed for 1,221 yards this season. Gerhart has gained 67 or more yards in three of the last four games, including 91 on Nov. 24 at Green Bay and 89 on 15 carries in last Sunday's 29-26 loss at Baltimore.

Peterson was knocked out of the Ravens game early in the second quarter with a sprained right foot. But he was out of his walking boot Wednesday, and Vikings fullback Jerome Felton said "he's walking around fine."

Peterson told reporters Monday that he expects to play against the Eagles. He expressed that to Frazier on Wednesday.

"He believes he's going to be ready to go," Frazier said. "But we'll give it a few days and see where we are at the end of the week."

If Peterson can't go, Gerhart is next in line. But Gerhart, battling a hamstring problem, also isn't expected to practice until Friday.

"I'm a little more optimistic with Toby than I am with Adrian," Frazier said. "But we'll see."

The third option is Asiata, who did make a fine block against the Ravens that helped turn a short pass to Cordarrelle Patterson into a 79-yard touchdown with 45 seconds left in the game. But it remains to be seen what he would do running the ball.

Asiata would want to provide some comfort to Cassel, the latest Minnesota quarterback to try to hold the job down.

Ponder has started nine games this season. He struggled against the Bears, completing 3 of 8 passes for 40 yards, before being injured. He wasn't cleared in time to be activated for the game against the Ravens.

Cassel completed 17 of 38 passes for 265 yards and two touchdowns against Baltimore.

Josh Freeman was signed Oct. 7, and his only appearance was a disastrous Oct. 21 outing against the New York Giants. Freeman likely will be inactive Sunday for the seventh time in 10 games, since Frazier said Ponder will be the backup.