CORY Gregson's nightmare run with injury has continued, with the Geelong small forward forced to undergo his fourth round of surgery on his troublesome left foot.

Gregson has suffered a fresh stress fracture with a screw inserted into his navicular bone on Monday and will miss the remainder of the Cats' 2018 campaign.

Coach Chris Scott on Monday night confirmed on Fox Footy's AFL 360 that Gregson's season was over.

"He has had surgery on his foot again after missing many years of footy," Scott said.

"You could make a strong argument that navicular stress fractures are a more serious injury than an ACL."

Geelong club doctor Drew Slimmon and head physiotherapist Mark Young were on hand for Gregson's latest round of surgery.

Gregson previously endured three separate surgeries on his left foot between 2016-2017 as he battled an ongoing navicular bone stress fracture.

The small forward was sent for scans last week after soreness in his foot stretched into a second week, finishing the July 8 VFL fixture on the bench.

Geelong's initial hopes had been for Gregson to play VFL on Sunday before the results of scans showed a new stress reaction.

Out of contract at season's end, the 21-year-old will hold hope of securing a fresh deal with Geelong having shown faith in its injured youngsters in recent seasons.

Gregson's return in round one against Melbourne this year had been his first AFL match in 638 days, his last coming in round 14, 2016.

He played the first four games of the season before a midfoot sprain in his left foot against St Kilda saw him miss round five. Featuring in the next five matches, Gregson was then dropped for the round 11 trip to face Gold Coast.

Gregson recently spoke of his journey to get back to playing in 2018.

"Rehab was tough. After my first and second surgeries, I was alone a lot in rehab," he told the AFLPA website in April.

"It was frustrating and difficult for my partner, who saw a less than happy side to me, and myself. At the start, I felt like there wasn’t a whole lot to look forward to.

"I'd get to the club and socialise with them (teammates) but they'd go off for a weights session and I'd be stuck in a moonboot.

"Even after I got out of the boot, my sessions were completely separate so I was still by myself. It can be a boring place.

"Watching the boys play was difficult, especially when things go wrong and you know you'd be able to contribute.

"They went down in a couple of finals while I was injured and it's frustrating not being able to help out in those situations."

Meantime, scans have found livewire Nakia Cockatoo re-injured his left PCL in the first 10 minutes of his VFL comeback on Sunday.

Playing for the first time since round three when he hurt his knee against West Coast, Cockatoo is set for more time on the sidelines with a timeframe yet to be determined.