Foles filled in for Vick and briefly rallied the Eagles until the Cowboys capitalized on turnovers and dominated the fourth quarter. The Eagles' 38-23 loss to Dallas on Sunday was their fifth straight, the longest losing streak in coach Andy Reid's 14 seasons.
Reid might not make it to Year 15. Vick might not make it to Sunday in Washington.
With a 3-6 record, it's likely too late for the Eagles, no matter who the quarterback is, to save their season.
"Not good enough to win," Foles said. "I made some mistakes and I can't turn the ball over. That's the most important thing to win games."
Foles hit the field in the second quarter and was greeted by a loud ovation from a crowd that had become fed up with Vick's erratic play.
Vick was knocked on his back by linebacker Ernie Sims on an incomplete pass and was slow to get up. He headed for the locker room and Foles started warming up. Vick, however, may have been injured on the previous play when he was driven from behind headfirst into the ground by tackle Jay Ratliff.
Vick did not talk to reporters but appeared groggy in the locker room.
The loss could speed up the countdown clock on Vick and Reid's time in Philadelphia.
In the final minutes, fans behind Dallas' bench unrolled a banner that read, "Andy, Quit, Your Team Has!"
Angry Eagles fans brought "Fire Andy!" and "This Is Not Acceptable" signs with them as they tailgated in the parking lots. There was at least one mobile billboard that read "Fire Andy Reid Now!!!" and "No Mas" with a pair of red Xs near the embattled coach's photo.
The 1998 Eagles lost their first five games of the season under Ray Rhodes.
Reid said he'd determine the starter for Sunday's game at Washington based on Vick's health
"I was hoping he'd make it through without having a concussion, but that's where we sit right now with him," Reid said.
Foles, a fan favorite without ever throwing a regular-season pass, looked like an instant hit and woke up a sleepy crowd in the third quarter when he hit Jeremy Maclin for a 44-yard TD and a 14-10 lead. Alex Henery's 40-yard field goal made it 17-10.
Foles was rolling, the Eagles were scoring, and the good times were back at Lincoln Financial Field.
But in a season unraveling with each bumbling defeat, the Eagles were knocked down to reality.
Tony Romo threw two touchdown passes, Dwayne Harris had a 78-yard punt return TD, and Brandon Carr returned an interception 47 yards for a score for the Cowboys.
The Cowboys (4-5) and are second in the NFC East, 1½ games behind the New York Giants, who lost to Cincinnati earlier Sunday.
The win, and a break in the schedule, could propel the Cowboys back in the thick of the division race. They will play five of their next six games at home, starting Sunday against Cleveland.
"Don't use words like desperate," Romo said. "The importance was at its highest level. I don't know if we are thinking anything more than we need another win."
Romo, who finished 19 of 26 for 209 yards, tied it with that TD pass to Bryant.
Dallas coach Jason Garrett had insisted the Cowboys weren't desperate after losing four of five. And they were dominant in the fourth period. The Cowboys need to keep playing like they did late on Sunday for a shot at catching the Giants.
Owner Jerry Jones refused to call the win a season saver.
"I don't want to do that," he said. "You can, but I don't want to do it. I know how important the game is to us."
Early in the final quarter, Foles had an interception return for a touchdown wiped out on a holding penalty. No worries, Dallas. Harris returned a punt 78 yards for a 24-17 lead that silenced the crowd.
On the next drive, Foles had an interception returned for a score that counted, by Carr, returned 47 yards for a 31-17 lead. Foles was 22 of 32 for 219 yards.
That was it for the fans in green, who fled for the exits. Stanley Havili had a 1-yard TD run with 1:55 left, but Henery missed the extra point.
Then Foles fumbled after he was sacked and Mike Jenkins recovered for a touchdown.
"Critical win for us," Garrett said. "I thought the effort was there. I thought we were focused the whole game. When you have success, you have to play through it, you have adversity, you have to play through it, and today was a good example of that."
The Eagles could have used some of that tenacity this season.
Vick, the four-time Pro Bowl quarterback, has struggled this season and entered with 10 touchdowns and nine interceptions.
He looked like his old self on the first drive, finishing it by connecting with Riley Cooper for a 2-yard TD. Cooper's sensational one-handed grab on a fade route gave the Eagles their first points on their opening drive all season.
The fun was short-lived when Romo hit Felix Jones on an 11-yard TD pass. Dan Bailey kicked a 30-yard field goal to send the Cowboys into halftime with a 10-7 lead.
NOTES: Foles was the first Eagles rookie QB to throw a TD pass since AJ Feely in 2001. Brian Westbrook, a running back, threw one in 2002. ... The Eagles had won six straight division games, including a sweep of the Cowboys. ... Eagles WR Jason Avant left with a hamstring injury. ... Sims started 15 games for the Eagles in 2010 and had two sacks.