Tennessee linebacker Rico McCoy is feeling more and more comfortable on the field.

That's a good thing, because the redshirt freshman likely will get his first career start Saturday.

Linebacker Jerod Mayo likely will be sidelined with a knee injury he suffered against Vanderbilt on Saturday.

UT coach Phillip Fulmer said Monday afternoon that Mayo, a starter at weakside linebacker, was doubtful for Saturday's 12:30 p.m. kickoff against the Wildcats (TV: WVLT) at Neyland Stadium.

Results of an MRI performed Sunday were inconclusive in large part because of swelling around Mayo's injured left knee.

"If Jerod could be out here, he'd be out here," Fulmer said before Monday's practice. "At the very least (it's) a bad bruise, could be a fracture. We'll find out more as it calms down a little bit."

Mayo, who missed five games in 2005 with a knee injury, went down late in the first quarter of Saturday's 39-10 victory at Vanderbilt.

He was on crutches and did not practice Monday, leaving a void on defense.

Mayo ranks third on the team in total tackles with 82, behind middle linebacker Marvin Mitchell and free safety Jonathan Hefney.

His 12.5 tackles for loss are a team high, as are his five sacks.

In Mayo's absence, McCoy filled in the final three quarters against Vandy and led the Vols with eight tackles, including three for loss.

Fulmer said he was pleased with McCoy's performance against the Commodores.

"Rico's a playmaker," Fulmer said. "He's young, and when you have a young player on the field there's going to be some mistakes along the way. But he makes up for a lot of his mistakes with his athletic ability and with his aggressive play."

That was on display on Vandy's final drive of the game when McCoy sacked backup quarterback Richard Kovalcheck and forced a fumble.

"I just thought I made a big play," McCoy said. "I was surprised the quarterback still had the ball when I got there, my eyes got big. I just wanted to make the play."

That play was wiped off the books because of a personal foul call, but McCoy followed that with two consecutive tackles for a loss.

"I was pretty upset they took the sack back and the forced fumble," McCoy said.

What he isn't upset with is the confidence he gained against the Commodores after struggling to get on the field earlier this season.

Despite playing in all 11 games this season -- and making at least a tackle in all of them -- McCoy was frustrated with his lack of playing time until the last few weeks.

"It has been (frustrating) at times," he said, "but it's a learning process, a growing process for me.

"I understood there was a bunch of things I had to learn. We had a couple close games where we needed all our starters out there and it really wasn't the place or time to come in and learn and get used to the game in those situations. I understood that, and I just tried to get better in practice."

He'll have to take another step forward this week against Kentucky and its offense, led by quarterback Andre Woodson, who leads the SEC in total offense and averages 266.7 yards passing per game.

"This is a different kind of attack, though," Fulmer said. "He's (McCoy) going to have to really do a good job in the passing game, too."