Colombo, who was injured toward the end of the day's second practice when his knee locked up, has been diagnosed with loose cartilage. If he undergoes arthroscopic surgery to clean it up, he could miss two to four weeks.
Colombo will be sent back to Dallas to undergo an MRI exam.
Robert Brewster, who can play both tackle spots, could also fill in for Colombo.
Colombo played the first nine games of the 2009 season before suffering a broken left fibula and a high ankle sprain. He didn't return until the playoffs. Prior to that, Colombo had been a durable player for the Cowboys.
"I think he'll be OK," offensive line coach Hudson Houck said. "I don't think it's any major problem. We don't want to miss him."
Colombo didn't miss a game from 2006 to 2008. But he's endured surgeries to both knees in his career and wears knee braces.
In 2002 when playing for the Chicago Bears, he suffered a dislocated left patella and femoral nerve damage. Colombo missed the entire 2003 season and part of the next season as he rehabbed the injuries.
The Bears released Colombo after the season opener in 2005 and he was out of football until the Cowboys signed him on Nov. 1, 2005.
He earned the starting right tackle job in 2006 and didn't miss a game until last year.