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

The 24-year-old is expected to miss up to a month of training.

Geelong general manager of football Steven Hocking said Duncan returned early from his off-season break and the injury flared last week.

"Mitch will have surgery this week and it is expected the recovery period will be around three to four weeks," Hocking said.

Duncan played 11 games in 2015, missing two months with a broken foot and then missing the final month of the season after sustaining a calf injury.