Something has to give.

"It's a great test for us," Vikings linebacker Ben Leber said. "Our strength against their strength."

The Falcons are powered by Michael Turner, a backup to LaDainian Tomlinson in San Diego for four seasons. Turner has paid major dividends since the Falcons traded for him and signed him to a six-year, $34.5 million contract. He is second to the Vikings' Adrian Peterson in rushing yards (1,421) and is tied for second with 15 touchdowns.

Leber, who played with Turner with the Chargers, isn't surprised by his success.

"Every time he came in, there was never a letdown when he was spelling L.T. I respect the guy," Leber said of Turner. "I knew the type of runner he was and how explosive he can be. They don't call him Burner Turner for nothing."

The Vikings will have to take on the best running back not named Peterson without arguably their most important run defender, defensive tackle Pat Williams.

Sidelined because of a fractured scapula, Williams will be missed.

"It's a tremendous loss," defensive coordinator Leslie Frazier said. "I don't care who you put in there, it's going to make a difference. We are going to miss him, but we are expecting Fred Evans, Ellis (Wyms) and other guys are going to have to step up."

Frazier said Kevin Williams could slide over, where he would line up over the center. But he added that Kevin Williams' strength is playing over guard.

"That's his strength, and that's why he's going to the Pro Bowl," Frazier said. "You don't want to take that away."

Injury update: Peterson was limited in practice Thursday, but he downplayed his ankle injury suffered Sunday at Arizona. Receiver Bernard Berrian got the day off.

"Letting the body recover," Berrian said, later adding that his body is "a little beat down."

"But who isn't that way?"

Coach Brad Childress said he expected defensive end Jared Allen to practice today after taking the past two days off to rest his ailing knee and shoulder. The good news is right tackle Artis Hicks and receiver Darius Reynaud practiced on a limited basis, an encouraging sign for both.

They missed the game against the Cardinals.

Briefly: Frazier marveled at the fact Falcons rookie quarterback Matt Ryan has been sacked only 14 times.

"That's an impressive number," he said. "A veteran quarterback maybe, but a rookie?

"We'll have our hands full trying to get him on the ground."

Special-teams coordinator Paul Ferraro said the blocked field-goal attempt against the Cardinals was a perfect storm of issues but added that the team expected to get that issue corrected.

Staff writer Rick Alonzo contributed to this report.