THE X-FACTOR: Tampa Bay running back Bobby Rainey

The Falcons know all about Tampa Bay running back Bobby Rainey, the flash from Griffin.

Rainey, who sliced through the Falcons’ defense for 163 yards last season in a 41-28 flogging in Tampa, will be the X-factor when the teams play at the Georgia Dome.

Rainey rushed for 144 yards on 22 carries against St. Louis on Sunday and will split carries with Doug Martin, who been out with a knee injury.

“He has great vision,” Tampa Bay coach Lovie Smith said. “What makes all good running backs good is that they know when to make the right cut. Bobby can catch and is an extremely smart player.”

Rainey also has caught five passes for 38 yards, including a 19-yard touchdown grab.

“I feel like he can do it all,” Smith said. “He can catch the ball out of the backfield. He can make you miss in the open field. He can run it in between the tackles.

The Falcons are giving up 154.4 yards rushing per game, which ranks 26th in the NFL. They were mauled for 170 yards by the Cincinnati Bengals and expect to see a heavy dose of Rainey and Martin.

The Falcons vow to be ready for Rainey this time around.

“He’s a very tough running back,” Falcons coach Mike Smith said. “He’s small in stature. We had a hard time tackling him when we played in the game down there last year. It’s going to be a challenge for us because Lovie and his staff are going to run the football. We’ve got to get better at it.”

As a rookie in 2012, Martin rushed for 1,453 yards.

Rainey, who has been cut three times by NFL teams, scored on touchdowns runs of 43 yards and 3 yards and caught a 4-yard touchdown pass in the rout of the Falcons last season.