GEELONG star Max Holmes will undergo surgery on Friday after suffering a right ankle fracture and syndesmosis injury in Thursday night's 27-point victory over St Kilda.

The hard-running midfielder was sent for further medical assessment after the match, with the club confirming the extent of the injury on Friday.

Holmes' right foot got trapped underneath him in a contest inside 50 in the fourth quarter, and he was in a moonboot and on crutches after the match.

Holmes' setback comes at a crucial stage of the season for the Cats, who banked an important win over the Saints to keep their top-six hopes alive but were left counting the cost on the injury front.

Geelong has not provided a return-to-play timeframe, with the club to wait until Holmes has made initial progress following surgery before outlining the next steps in his recovery.

The injury is a significant blow given Holmes' importance to Geelong's midfield mix, where his pace, running power and ability to break lines have been key features of his game.

"It was pretty clear that he couldn't come back on, so that's always my measure in the immediate aftermath," coach Chris Scott said after the match.

"I think everyone says syndesmosis these days. There has been that suggestion but I covered my ears, to be honest. I'll just wait to see what it is and deal with it when we know."

Forward Shaun Mannagh (hamstring tightness) also finished the match on the bench.

Last week the Cats lost spearhead forward Jeremy Cameron for four to six weeks with an AC injury that required surgery during the week.

The Cats ended a three-match losing streak with a comprehensive 15.12 (102) to 11.9 (75) win over the Saints.