The senior captain, who has never missed a game in his career, won't play in the No. 17 Wolverines' opener against Central Michigan after having the procedure to remove damaged cartilage in his right knee.
Avery is questionable for Michigan's next game, against No. 14 Notre Dame.
Avery's knee had been bothering him for a while and limited him in practice. But recent swelling caused him to get an MRI.
"It's definitely frustrating," Avery said. "Especially my senior year, I wanted to spend every second out there that I could on the field with my teammates. That's just not how it worked out. You just sort of have to roll with the punches."
Avery, with 81 career tackles, eight pass-breakups, three forced fumbles and two interceptions, had switched to free safety from cornerback during fall camp.
Michigan will likely turn to redshirt junior Josh Furman, sophomore Jarrod Wilson or freshman Dymonte Thomas in his absence. Furman has appeared in 12 games for Michigan as a defensive back, accounting for 18 total tackles. Wilson played in six games last season for the Wolverines, registering eight tackles. Thomas enrolled early, which gives him a jump on other true freshman defensive backs.
"Even when I was playing, I did a lot of teaching to the younger guys," Avery said. "Now, I'm more coaching on the sideline and pulling them aside if Coach [Curt] Mallory is busy with some guys on the field, I can pull them aside off the field and talk to them."