Coan suffered a non-contact injury to the foot during practice Saturday, and Wisconsin confirmed he will be out indefinitely.
Coan had been the starter last season for the Badgers, throwing for 2,727 yards and 18 touchdowns with five interceptions. He helped guide Wisconsin to a Rose Bowl appearance and Big Ten West divisional title.
Speaking to reporters on Monday, coach Paul Chryst said redshirt freshman Graham Mertz is now No. 1 on the depth chart, with redshirt sophomore Chase Wolf and redshirt junior Danny Vanden Boom behind him.
"Graham's been our second quarterback with Jack as the starter and Graham is taking all the reps with the ones, then we got Chase and then Danny get the rest of the work," Chryst said. "Continuing to move forward, I think this is a big week for us coming up."
Mertz was the No. 21-ranked prospect in the 2019 class and the highest-ranked quarterback to sign with the Badgers. He completed 9 of 10 passing for 73 yards in two games last season, and Chryst says he has full confidence in Mertz or any of the quarterbacks on the roster.
"I don't feel that any of the quarterbacks necessarily are so different that you're limited or you can do a lot of one thing and not much of another thing because of who's at quarterback," Chryst said. "System-wise and your offense and your offensive playbook can be similar, but then it's, 'What does each guy do well and how do you play to their strengths that way?' Not necessarily schematically, it's more you just put them in a good position to play efficiently and effectively at the quarterback spot."
There isn't a timetable yet on Coan's return, but Chryst told reporters his quarterback's attitude hasn't changed and he's continuing to move forward in the process.
"He's incredibly unselfish. He cares about this team and doesn't want anything to affect the team in a negative way," Chryst said. "He's pretty neat that way. His focus is not about him and feeling sorry for himself, he does focus on the guys and this team. It's what you love about him last week when I was talking about him and love about him today."