ATHENS — Mike Gilliard had never started a game before Georgia lost linebackers Alec Ogletree and Christian Robinson to injuries the first two weeks of the season.
    Four games later, Gilliard is Georgia's leading tackler and the Southeastern Conference's defensive player of the week.
    Gilliard had 12 tackles, a forced fumble and a sack in last week's 20-12 win at Tennessee to win the SEC honors. The junior has helped the Bulldogs, who play at Vanderbilt on Saturday night, overcome the injuries to win four straight games.
    Now that he has so successfully seized the starting job at inside linebacker, Gilliard said Tuesday he doesn't want to let go.
    "I'm going to try my hardest to hang on to it," Gilliard said.
    Soon, Georgia coaches may face some tough decisions at the two inside linebacker spots in the 3-4 defense. Robinson has played a reserve role the last two weeks. Ogletree, who broke his foot in the opening loss to Boise State, is expected return in the Oct. 29 game against Florida.
    Gilliard keeps making stops in his bid to preserve his starting role. But what happens when Ogletree returns?
    "As of right now, I really don't know," Gilliard said. "Alec, he's a really good player. I'm interested to see what's going to happen when he comes back. I'm just going to keep working hard and doing my part and time will tell."
    After losing its first two games, Georgia (4-2 overall, 3-1 SEC) has moved into a tie for first in the Eastern Division. With Gilliard playing a key role in the middle, stingy defense has led the team's recovery.
    Georgia ranks sixth in the nation in total defense. The defense has allowed only two touchdowns in the four-game winning streak, marking a dramatic recovery after the team allowed a combined 80 points in the opening losses to Boise State and South Carolina.
    "I don't want to get too excited yet, but I'm feeling like we've built a very good foundation on defense," coach Mark Richt said Tuesday. "I'm hoping the best is yet to come. I think we are gaining confidence."
    Richt says the defense played better than the scores indicated in the loss to South Carolina. The Gamecocks scored touchdowns on punt, fumble and interception returns and set up another touchdown with a fumble return.
    Since then, the defense has gained momentum.
    Georgia held Tennessee to minus-20 yards rushing, the low mark for the defense in Richt's 11 seasons. The Bulldogs rank 12th in the nation against the run.
    "If you can start out by stopping the running game, it's huge," Richt said. "We've done a really good job with that, which has allowed us to get people out of their game plan a little bit."
    Vanderbilt coach James Franklin said he can see improvement in the Georgia defense in its second year with coordinator Todd Grantham.
    "I think he's doing a really, really good job," Franklin said. "I think obviously year two makes a world of difference for everybody. You can see a big difference in their defense how they're playing right now."
    Gilliard leads Georgia with 40 tackles, including only a combined four in the first two games. His production as a starter has steadily improved as he has joined freshman Amarlo Herrera at inside linebacker.
    Gilliard said he has logged extra time in the film room and has worked harder in practice to help him win the starting job.
    "Personally, I just feel like when Alec and Christian were out, that was my time to step up," Gilliard said. "I just feel it was my time to go out there and make plays. I did all the extra stuff. I watched film, went the extra mile at practice and things like that so that when I went out there I just tried to make plays."
    Richt said Gilliard has "really studied hard."
    "He's really been a very physical tackler, he's been a sure tackler, and he's had very few missed assignments," Richt said.
    The extra studying has helped Gilliard make up for his lack of experience.
    "He's doing a pretty good job of learning to communicate back there," Richt said. "That's one of the things we all know that Christian Robinson had to his advantage, his ability to know what was going on and not only to get himself lined up but get other people lined up and make quick adjustments to motions and formations and shifts."

Linebacker, which looked dangerously thin at the start of the season, suddenly is a deep position for Georgia. Richt said Tuesday "I don't think there's any question" Ogletree will return for the Florida game.

"In the meantime," said Richt, "Amarlo has grown up some and Gilliard has grown up a bunch."