Kansas University’s football team will face the nation’s sixth-best defense without the Jayhawks’ best offensive weapon.

Quarterback Bill Whittemore  who injured the medial collateral ligament in his left knee during last Saturday’s 36-12 loss at Missouri  will not play in Saturday’s home game against No. 14 Kansas State, coach Mark Mangino said Thursday night.

Head athletic trainer Carol Jarosky had treated Whittemore during the week in hopes the junior might be able to play.

“Bill is improving daily, but not to the point where he is ready to play this Saturday,” Jarosky said.

Senior Jonas Weatherbie will make his first collegiate start and will be backed up by red-shirt freshman Brian Luke.

“Both of them are ready,” said Whittemore, who ranks third in the Big 12 Conference in total offense with an average of 246.1 yards per game. “They’ve been waiting for this opportunity.”

Weatherbie has been waiting a long time. The career backup has completed 3-of-10 passes for 26 yards in nine career college games.

KU (2-7, 0-5 Big 12) was a 311â2-point underdog before it was announced Whittemore won’t play. Weatherbie will face a Kansas State team (6-2, 2-2) that ranks sixth in the nation in total defense (267.6 yards per game), fourth in rushing defense (76.6 yards per game) and fourth in scoring defense (13.4 points per game).

“They’ve got some great talent on defense,” Weatherbie said. “They fly around. They’ve got some good linebackers, good linemen and secondary. There’s not too many weak links to that defense. We’ve just got to protect the ball and try to get some big plays on them.”

Weatherbie (6-foot-2, 200 pounds) completed 1-of-6 passes for 10 yards last week after replacing Whittemore late in the third quarter. That was his first appearance at quarterback this season.

Luke (6-5, 215) hasn’t played at all. The red-shirt freshman broke the thumb on his passing hand in the final two-a-day scrimmage and wasn’t cleared for full participation until Oct. 21.

Offensive coordinator and quarterbacks coach Nick Quartaro said Luke’s feel for the ball hasn’t been hindered because of his injury.

“There’s only an occasional ball that has a wobble to it,” said Quartaro, who said Luke has the strongest arm of all KU’s quarterbacks. “I’m really amazed at how he’s doing. He hasn’t missed a beat, and now he’s getting more repetitions and preparing to play.”

Mangino didn’t say when, or if, Whittemore could return to the lineup. Kansas has two games remaining Â- next Saturday’s contest at Nebraska and the season finale the following week at home against Oklahoma State.

“Our players and coaches are confident in Jonas and backup Brian Luke,” Mangino said. “They both have had a very good week of practice and look sharp.”

Weatherbie, the son of former Navy coach Charlie Weatherbie, will have at least two fans in the stands. His father has attended every KU game this season.

“Him and my mom are very supportive, playing or not playing,” Weatherbie said. “They are behind KU 100 percent.”