The Blue Devils announced Saturday that Sirk had suffered a partial tear of his left Achilles during practice Thursday. He will undergo surgery to repair the tear.
This marks the third injury to an Achilles tendon since 2013 for Sirk, a redshirt senior who led Duke in rushing and passing last season and was the co-MVP of the Blue Devils' New Era Pinstripe Bowl victory over Indiana.
Sirk passed for 2,625 yards and 16 touchdowns and added a team-best 803 yards rushing and eight touchdowns during his first season as Duke's starter.
He tore his left Achilles tendon during an offseason conditioning workout Feb. 9 but set a goal of returning for the start of preseason practice, saying the experience of coming back from the same injury to the other tendon would help with this rehab. He missed all of 2013 after tearing the right one that April.
News of Sirk's latest injury was first reported by the Durham Herald-Sun.
Redshirt freshman Daniel Jones had been taking most of the first-team snaps during practice, according to coach David Cutcliffe, as the team waited to see whether Sirk would be ready.
The Blue Devils begin the season Sept. 3 against North Carolina Central of the FCS.
The Associated Press contributed to this report.