Sources: Duke's Riley Leonard out extended time with toe injury

Riley Leonard exits after apparent leg injury (0:30)

Duke QB Riley Leonard limps off the field after being sacked by Florida State's pass rush. (0:30)

Duke quarterback Riley Leonard will miss an "extended period of time" with a left toe injury suffered late in the game against Louisville on Saturday, sources told ESPN.

His absence against Wake Forest on Thursday night means that true freshman Grayson Loftis will get his first career start. He's thrown just five total passes in his career.

A definitive timetable on Leonard's potential return from this injury has yet to be determined, per sources. It's not a certainty that he'll be back this year, per ESPN sources, although any possibility of a return would come much later in the year.

Leonard emerged this year as one of the sport's breakout stars, leading Duke to its highest Associated Press poll ranking -- No. 16 -- since 1994. He's thrown for 1,102 yards and three touchdowns and is also Duke's third leading rusher with 352 yards and four touchdowns.

The toe injury is different than the high ankle sprain he suffered late in the game against Notre Dame on Sept. 30 that forced him to miss one game earlier this season. He re-aggravated that ankle injury against Florida State two weeks ago before hurting the toe on the opposite foot last week against Louisville.

Duke went 9-4 last year in Leonard's first season as a starter, which coincided with coach Mike Elko's arrival in Durham. The Blue Devils are 5-3 this season and one win from back-to-back bowls, a significant accomplishment at a program that's reached just 15 total bowls in program history.

Duke has lost two straight games after opening the season 5-1, which included a statement 28-7 win over Clemson to open the season. Duke is 2-2 in ACC play after starting conference play 2-0 with wins over the Tigers and NC State.

Duke's normal back-up, Henry Belin IV, is still dealing with an upper-body injury and is expected to be limited against Wake Forest. His injury allowed Loftis to take first-team reps in practice this week.

Leonard's toe injury appeared to emerge late in the game against Louisville. He was visibly hobbling after a long fourth-quarter completion with nearly seven minutes remaining. Loftis replaced him on the next drive with about four minutes remaining.

Wake Forest (4-4) is expected to enter the game healthy at quarterback, as starter Mitch Griffis returned last week after missing the Pittsburgh game two weeks ago with an undisclosed injury.