MANKATO, Minn. -- When defensive tackle LeTroy Guion rolled up on Tarvaris Jackson's left knee in practice on Saturday, the Minnesota Vikings' quarterback competition nearly ended before it really started.
Much to Jackson's relief, the injury was not nearly as serious as it first looked and he expects to be back on the field competing for the starting job in no time.
Jackson sprained the MCL in his left knee, but avoided any serious injury, a person with knowledge of his condition told The Associated Press. The person requested anonymity because the team did not make an official announcement.
Coach Brad Childress declined to divulge the specific injury, but said Jackson would be OK.
"It looks like he'll be just fine," Childress said.
It was still a scary sequence for the Vikings. During an 11-on-11 drill in helmets, shoulder pads and shorts in the morning practice, Guion got tangled up with a few offensive linemen and fell to the ground just as Jackson was stepping up in the pocket. The 303-pound tackle rolled up on Jackson's leg, the kind of play that has often inflicted far more serious damage.
"I really don't know what happened," Guion said. "Everybody was moving so fast."
The fourth-year pro first received some attention at a tent on the side of the field before heading to the team's locker room area at Minnesota State University, Mankato. He got an MRI, which revealed the most mild form of a sprain, and the rest of the team breathed a sigh of relief.
Jackson is in a competition with Sage Rosenfels for the starting quarterback position after Brett Favre decided not to come out of retirement and join the Vikings.
"We're competing out here and I'm sure he'll be back," Rosenfels said. "You never want to see anyone with an injury, even an opponent much less your own teammate."
In his four seasons in the pros, Jackson has had to deal with multiple injuries. He tore the meniscus in his right knee during his rookie season, missed two games with a strained groin, one with a broken finger and one with a concussion in 2007. He sprained his right knee in the preseason last year but did not miss any regular-season games because of it.
"Whether it's Tarvaris or any of your guys, you don't want to see any of your guys go down, no matter who it is," offensive coordinator Darrell Bevell said after practice. "Whether it's your quarterback, your third tight end, it doesn't matter. You don't like to see anybody have any type of injury."
The Vikings have held three practices since training camp began on Friday, and Jackson and Rosenfels have been splitting the snaps with the first team.
"It's pretty tough [to see that], especially in practice," left tackle Bryant McKinnie said. "Hopefully he'll be all right."
In his first season on the job in 2006, Childress drafted Jackson in the second round as his quarterback of the future. He has been up and down in his first three seasons in the league, which led to the recruitment of Favre all summer long.
When Favre called Childress on Tuesday to tell him he wasn't coming, the competition started anew for Jackson and Rosenfels.
Jackson's familiarity with the offense appears to have given him a slight edge so far, but it's still very early in the competition.
"At this time, Tarvaris has a little bit more knowledge of our system," Bevell said. "He is an athletic quarterback. He's got a very strong arm and those would be the positives about him."
Childress said there was no need at this point to bring in another quarterback to help out Rosenfels and third-stringer John David Booty in practice, a telling statement on the health of Jackson.
Jackson missed the Vikings' practice on Saturday night. If he can't go for the team's lone practice on Sunday, Rosenfels and Booty will get all the work.
"You can't put a price on the elevated snaps they're getting," Childress said.