Mike Hartline tried unsuccessfully to give it a go against Vanderbilt on his bad left knee on Saturday.
Now, the junior quarterback will undergo surgery on Tuesday to repair the cartilage in that knee.
Hartline will miss Kentucky's final two regular season games but is expected to be ready for UK's bowl practices. The Wildcats qualified for bowl eligibility with its 24-13 win over the Commodores.
Hartline sustained a torn medial collateral ligament and torn cartilage on Oct. 10 during the South Carolina game. Hartline sat out four games before returning in a backup role against Vandy. But Hartline went just 2-of-6 passing for 10 yards and appeared to be favoring the knee on several occasions.
"When the game starts flying as fast as it does in the SEC and (he would) try to plant and move and go, it just wasn't functioning correctly, so we decided to go ahead and get (surgery) done on Tuesday morning," Kentucky Coach Rich Brooks said.
Freshman Morgan Newton will stay at quarterback with occasional doses of receiver Randall Cobb in the Wildcat formation. Newton has started the last five games, completing 58.9 percent of his passes (43 of 73) for 402 yards and two touchdowns with three interceptions while rushing for 86 yards and two scores.
Brooks said he expects Cobb to take the same amount of snaps he has taken in the 'Wildcat' since Hartline went down, which has ranged between 10 and 18.
Newton has shown gradual progress as the starter, but the passing game hasn't been as consistent. Thanks to a 144-yard rushing performance by Derrick Locke and 99 more by Cobb, UK rushed for a season-high 308 yards against Vanderbilt. But the Wildcats were just 7-for-15 passing for 91 yards with two picks.
Brooks said he remains pleased with how Newton is coming along.
"He certainly managed checks better than he did earlier," Brooks said. "When we did ask him to throw, he threw it very well. His one pick was a tip. We just decided in the second half to pound the football. We were able to get into a lot of third-and-shorts, so we didn't feel like we needed to throw."
But Brooks also knows the passing game must show more life under Newton if Kentucky is to have any chance against the Bulldogs and Volunteers
"We're certainly not going to run for 308 yards on Georgia's defense," Brooks said. "We need to get (Newton) functioning really well in the passing game. He's gotten better at practice each week, and against Eastern Kentucky he had a very good day throwing. Now he's going to have to do it against a talented SEC defense. It'll be a bigger challenge."
In other injury news, Brooks said that Cobb suffered a bruised shoulder in the Vandy game while junior receiver Chris Matthews sustained a mild concussion. Brooks expects both players to be able to return to practice by Tuesday or Wednesday.
Big Blue Crush begins
The annual Big Blue Crush, a blood-drive competition between Kentucky and Tennessee football fans, is set to run Monday through Friday. Tennessee leads the annual competition 11-9-1.
All donors will receive a free menu item from McDonald's and a Big Blue Crush T-shirt.
In addition, anyone who registers to donate on Monday or Tuesday will be entered in a drawing to win a Nintendo Wii. Donors Wednesday through Friday will be eligible to win a football autographed by Coach Rich Brooks.
Donors must weigh at least 110 pounds, be in general good health and have a photo I.D. To find a donation location, call 1-800-775-2522 or visit www.kybloodcenter.org.