Nat Fyfe looks on during the AAMI Community Series clash against West Coast on March 6, 2022. Picture: AFL Photos

TWO-TIME Brownlow medallist Nat Fyfe will miss at least six weeks after undergoing surgery on his back over the weekend.

The Fremantle captain has missed their opening two games of the 2022 AFL season following off-season shoulder surgery where a subsequent infection delayed his return to pre-season.

Fyfe's latest issue relates to a disc in his lumbar spine, which required an operation on Saturday.

"I had to have a little operation on Saturday that went really smoothly," Fyfe told Triple M Perth.

"I'm up walking around already and I'll hopefully start running within two weeks and look to be playing in somewhere around six weeks, but these things are a bit subjective based on the individual."

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The 30-year-old has only managed 29 games since the start of the 2020 season and warned that the back injury would need diligent rehabilitation.

Nat Fyfe talks to media during Captains Day at Optus Stadium on March 9, 2022. Picture: Getty Images

"The back will recover fully and I'll be playing footy this year," he said. "But with backs, I've spoke to Matt Pavlich extensively about this, you have to really respect it because you don’t want any other lingering problems."

The Dockers' football boss Peter Bell said Fyfe's prognosis was good.

"He is going really well, he is upbeat and positive," Bell said.

"We will give it another couple of days before he will be assessed again on when he can commence running.

"At the time of the surgery, it was told to us that it would be a couple of weeks before he begins running, and then a return to train and play after that."

Meanwhile, veteran onballer David Mundy will miss Sunday's Western Derby with his stint in the AFL's health and safety protocols to extend beyond the weekend.

David Mundy during Fremantle's official team photo shoot at Cockburn ARC on January 25, 2022. Picture: AFL Photos

The 36-year-old midfielder, who won the Ross Glendinning Medal in 2013 for best afield in the derby, had entered protocols prior to the round two loss to St Kilda.

Bell revealed ruckman Sean Darcy (ankle) and forward Matt Taberner (hamstring) were in contention to play in the derby.

"Sean turned his ankle pretty sharply in the third quarter against the Saints," Bell said.

"There is a lot of swelling there and we will see how that progresses over the next couple of days, but there is a possibility that he will be available this week.

"Matt is progressing really well, he had a great session on the weekend and will do another big session at main training on Thursday."

Fremantle's Matt Taberner celebrates a goal during a practice match against West Coast on February 25, 2022. Picture: AFL Photos

Nathan Wilson and Josh Treacy will also face fitness tests after shoulder and ankle injuries respectively.

West Coast revealed that wingman Andrew Gaff (foot) and utility Jackson Nelson (knee) will also be tested later in the week as they seek to prove their fitness for Sunday's game.

Two-time club champion Elliot Yeo returned to training on Tuesday after a calf injury but is still listed as two weeks away from a return to play.