Geelong midfielder Mitch Duncan will have the start of his pre-season delayed by minor surgery near his achilles.

"Mitch returned early from his off-season break and the injury flared during a session last week," Geelong's general manager of football Steve Hocking said.

"Mitch will have surgery this week and it is expected the recovery period will be around 3-4 weeks."

Duncan missed most of 2015 with a foot injury suffered against Sydney in round seven.

The majority of the Cats squad returned to training on Monday except for Patrick Dangerfield and Harry Taylor who are returning from Ireland after the International Rules Series.