SOUTH BEND, Ind. (AP) Notre Dame coach Brian Kelly is worried about the number of season-ending injuries hitting the sixth-ranked Fighting Irish.

''Certainly we can't afford to lose any more players at key positions: Quarterback, running back, you start to get into true freshmen, and that will be obviously a significant change in what we look like,'' Kelly said Sunday.

Sophomore safety Drue Tranquill became the sixth player for the No. 6 Fighting Irish to sustain a season-ending injury when he tore the anterior cruciate ligament in his right knee Saturday while celebrating a pass breakup in the end zone against Georgia Tech.

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Tranquill sustained the injury just before halftime and spent the second half on the sideline on crutches with a brace on his knee as the Irish held on for the 30-22 victory.

Kelly said Tranquill is expected to undergo surgery within two weeks after doing some rehabilitation work. Tranquill was making his first start of the season after starting three games last season, when he missed the final two games with a torn ACL in his left knee.

''Drue Tranquill was a very important player in our back end of the defense because of his versatility. So there is a break point,'' Kelly said. ''We're still at a point where we have guys that can come in and step in, but there's no question that we have to be able to stem the tide here with the injuries.''

The injury leaves the Irish short-handed at safety, but Avery Sebastian, a transfer from California who broke a bone in his foot against Texas is expected to return in mid-October.

Kelly has said he doesn't believe there's anything that can be done about the rash of injuries, pointing out that the injuries have occurred in a variety of ways on grass and artificial surfaces.

Defensive lineman Jarron Jones was the first to go down in mid-August with a torn medial collateral ligament in his right knee when at the end of a play Notre Dame tackle Mike McGlinchey pushed linebacker Joe Schmidt, who fell in to Jones. Freshman nickel back Shaun Crawford , who had been practicing with the starters, during a one-on-one drill when he was backpedaling, turned and planted and tore his ACL.

Running back Tarean Folston, who led the Irish in rushing last season, tore the ACL in his right knee on his third carry of the season against Texas. Quarterback Malik Zaire fractured his ankle when his leg got trapped under a Virginia player on a run. Tight end Durham Smythe tore the MCL in his right knee in the final minute when a teammate fell into his leg.

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AP college football website: collegefootball.ap.org