GEELONG captain Joel Selwood will have surgery on his left ankle after scans confirmed he suffered a syndesmosis injury in Friday night's 46-point loss to Sydney.

However, the club expects the 29-year-old to be available in time for the finals in just over a month.

Selwood will miss home and away matches against Richmond, Collingwood and Greater Western Sydney in a massive blow to the Cats' top four hopes.

Geelong is currently in fourth place, a game and half clear of Port Adelaide, Sydney and the Western Bulldogs.

The Cats released a statement on Sunday evening, saying surgery was deemed the best option after "consulting with specialists in the field".

Selwood, who was on crutches over the weekend, hurt ankle in two separate incidents against the Swans.

He first rolled the outside of his ankle when he stood on teammate Zac Smith's foot in a marking contest late in the second quarter.

Selwood was unable to put weight on his left foot as he left the field in the hands of the club's medicos.

He had his ankle strapped and performed a fitness test in the rooms during the main break, before starting the third quarter on the ground.

Selwood then suffered the more severe injury to the same ankle late in the third term as his leg got caught under a Buddy Franklin tackle – this time twisting inwards – which left him hobbling at three-quarter time.

The tough skipper began the last term on the ground but was wrapped in cotton wool a few minutes later, with the club deciding to not risk him further.

The ankle syndesmosis is the joint between the tibia and fibula bones.

Speaking post-match, Cats coach Chris Scott painted a rosy picture of Selwood's injury.

"I'm actually confident enough now to say he'll be fine," Scott said.

"Clearly in the last quarter the discussion was around whether we should be pushing him through and make his chances of playing next week lower. So, given that, we sit here pretty confident that he will be OK."

Selwood has played all but one game this season, missing the round 15 draw with the Giants due to concussion he suffered a week prior against Fremantle.

Geelong will be aiming to take a leaf out of the Western Bulldogs' book in a bid to fast track Selwood's return after midfielder Tom Liberatore had surgery last season to repair a syndesmosis injury suffered in round 19.

Liberatore missed the last four rounds of the season before featuring in each of the Bulldogs' finals, including the drought-breaking premiership win.

Greater Western Sydney midfielder Stephen Coniglio, meanwhile, missed the first six rounds of the season with the syndesmosis injury he suffered in the Giants' final JLT Community Series hit-out.

He then missed another 10 weeks after picking up a second syndesmosis injury against Collingwood in round eight, returning against Fremantle in round 19.