Kevin Kolb will be under center if McNabb can't play because of a cracked rib suffered in Philadelphia's dominant 38-10 win at Carolina.
Garcia, who led the Eagles to a division title and a playoff victory after McNabb injured a knee in 2006, was signed this week as insurance. He briefly played with Oakland in the preseason before getting released Sept. 5.
Vick is not eligible to play because he was suspended for the first two regular-season games as the final league penalty for his role in running a dogfighting ring. He probably wouldn't start even if he was allowed.
That leaves Kolb, a second-round pick in 2007 who has only seen meaningful action one time. He replaced an ineffective McNabb at halftime of a 10-7 game at Baltimore last November and played poorly as the Eagles got routed.
Once billed as the future franchise quarterback, Kolb hasn't gotten much of a chance to show his stuff because McNabb is still playing at a high level. In his rare appearances, Kolb has struggled.
He is 24 for 45 for 167 yards and four interceptions in eight career games. He was 7 for 11 for 23 yards and got sacked twice against the Panthers. The Eagles already were up by 28 when he replaced McNabb.
"I think he's done a nice job," coach Andy Reid said. "I think we all keep in mind that he's a young guy and doesn't have a lot of experience, so there might be a misfire here and there. Overall, I feel very comfortable with him in there knowing the offense. He's very well-advanced knowing where people are and the defenses that he's playing against, and I think he's got a great feel for the game. I think between myself and the coaches and the players, we all have a lot of confidence that he'll go out given the chance and perform very, very well."
With a talented group of QBs surrounding him, Kolb knows where to turn for advice as he prepares for his first NFL start.
"I've leaned on them a lot already," he said. "Jeff and I have talked just in the short time that he has been here quite a bit. That's amazing, really. The 12 Pro Bowls with those three guys and you just never think you're going to be in the same room with all three of them. So, that's a blessing and I'm glad I'm the guy that's in there."
McNabb's uncertain status made it tougher for New Orleans to prepare defensively for the Eagles.
"There are a lot of weapons we have to account for," Saints coach Sean Payton said. "We start with Brian Westbrook. They have a lot of team speed. It's a little more challenging trying to envision which quarterback. The one thing that has made it difficult to defend Donovan is the amount of plays he's able to extend, step up in the pocket, flush, break you down on third down. In Kevin's case, you don't have that history of film. We have to be ready for an offense that's explosive."
Westbrook, Philly's all-purpose running back, and speedy wide receiver DeSean Jackson will be counted on heavily if McNabb can't go.
"It all starts with Westbrook," Saints safety Darren Sharper said. "He's the guy that drives the ship. Whenever you have a guy that accounts for 40 percent of the offense, you always have to be aware of where he is. The one guy who has become very explosive is DeSean Jackson. He's a guy that once he gets the ball in his hands, he can go all the way to the end zone. We have to be very careful with him, too."
New Orleans has no concerns at quarterback. Drew Brees will be eager to add to his TD totals after throwing for six scores in a 45-27 win over Detroit.
Brees had success against the Eagles in 2006 when the Saints reached the NFC championship game. He threw for 275 yards and three TDs in a 27-24 win during the regular season. He had 243 yards passing and one TD in a second-round playoff victory by the same score later that season.
Philadelphia's defense also has to be wary of the Saints' rushing attack. Mike Bell, filling in for an injured Pierre Thomas, had 143 yards rushing against the Lions. Thomas is expected to return from a knee sprain, but Bell will get some carries. New Orleans also has the dangerous Reggie Bush in its backfield.
"You have to watch out for their running game," Eagles defensive tackle Mike Patterson said. "They're a good all-around team. They have a good passer and they have good runners and that offensive line is big and solid. They have physical guys who can block."