Philadelphia quarterback Michael Vick is the X-factor for the game Sunday night against the Falcons. He is the player, with a bevy of weapons, who can flip the game in favor of his team with a single play or a string of plays.

While he has progressed as a passer in Philadelphia, he’s still a dangerous runner. He rushed 11 times for 97 yards in the Eagles’ season-opening win over the St. Louis Rams on Sunday.

The Falcons are coming off a game where they had 17 missed tackles, according to head coach Mike Smith.

“I think everybody has to be conscientious of their rush lanes and try not to get too many people on one side of him,” Falcons defensive tackle Corey Peters said. “We have to try to keep him in the pocket. You can’t be tentative. You really still have to go after him.”

Vick has weapons in wide receivers DeSean Jackson, running back LeSean McCoy and wide receiver Jeremy Maclin. Jackson (two touchdowns) and Maclin (seven catches for 159 yards and two touchdowns) caused the Falcons trouble last season, and that was without Vick.

“I think everybody knows he’s one of the most difficult guys to stop because he’s the best running quarterback to every play the game, and his passing is very much improved,” Peters said. “I think he’s a top-five quarterback passing the ball as well.”

Teams that have been successful against Vick have blitzed from his left side to flush him to his right. He’s left-handed and is considered more dangerous when he scrambles to his left.

“The No. 1 thing is to keep him in the pocket,” Falcons middle linebacker Curtis Lofton said. “We can’t let him break outside. It’s just going to take a group effort, and we have to mix up our blitzes and coverages. We must get to him and hit him.”

Vick completed 14 of 32 passes for 187 yards for two touchdowns and threw no interceptions against the Rams.

“It’s a challenge, and what you have to do is be very disciplined in everything that you do because he has a strong arm and can make the throws,” Smith said. “If the throws aren’t there, and if you aren’t disciplined with your pass rush, he’s going to hurt you with his feet. It’s a big challenge for our defense.”