Urrurita hurt his knee late in the Cardinals 46-44 triple overtime loss on the road at West Virginia last weekend.
"It was late in the game and a guy dove over the top pile and landed on him," explained Petrino.
Petrino said he's not sure when the 6-6, 220-pound Urrutia might return. Following the press conference, however, Urrutia was seen walking through the parking lot under his own power without the uses of crutches.
"I don't believe we'll have Mario (Urrutia)," Petrino said. "I'm not sure how long he'll be out, but he'll be out for a while."
Besides Urrutia, the Cardinals will also likely be without three additional starters when they travel to Cincinnati this weekend to play the Bearcats.
"We're down a few guys and that's the thing that is a concern for me," said Petrino.
Junior running back Kolby Smith continues to make progress toward a return to action, but Petrino said the Cardinals second-leading rusher's status is anything but certain for this weekends game.
"Kolby Smith is still up in the air," Petrino said. "If it (the game) were yesterday, I'd say we won't have him. But he is improving all the time."
Wide receiver Broderick Clark was slated to return against West Virginia, but an injury during practice late last week has put the 6-0 senior back on the shelf.
"Broderick Clark was supposed to play last Saturday, then on Thursday he shook his knee up a little bit and it swelled up on him and couldn't go (against WVU)," Petrino said. "I don't know if he'll be back."
On defense, junior linebacker Abe Brown will also likely miss the Cincinnati game.
"Abe Brown is still out, so we've got a lot of starters that won't be there (Saturday)," said Petrino.
"We've got to get some young guys ready to go," Petrino said.