Lachlan Croker was never in doubt that what's likely to be a 421-day wait since last wearing the No.6 for Manly would eventually end.

Croker, who will replace injured five-eighth Dylan Walker in Sunday’s match against Cronulla, has played just 19 matches for the Sea Eagles in the past three seasons but has never been dropped from his preferred position.

"That's definitely a positive," Croker said. "As a kid, all you want to do is play football and be in this position but you never want to be part of the team because of injury so it’s bittersweet."

If anyone is qualified to know how injured Sea Eagles duo Walker (ankle) and Tom Trbojevic (hamstring) feel it is Croker.

After playing alongside Daly Cherry-Evans for the first eight rounds of the 2018 season, he injured his knee and required a reconstruction that sidelined him for 12 months.

Turbo, Walker double blow for Sea Eagles

A triumphant return against his former club, Canberra, in which Croker scored two tries, was followed by the frustration of another stint on the sidelines after suffering a hamstring injury the following week against Canterbury.

"I feel like that has been the story of my life so far but that is footy and that's the way it goes," Croker said. "There's a lot of ghosts that I have got in my background. It is pretty scary thinking about what has happened before."

Croker has since played nine more games for the Sea Eagles as an interchange utility but the match against Canterbury on May 4, 2019 was the last time he started at five-eighth.

With Walker assisted from the field in just the third minute after injuring his ankle in a tackle by Raiders forward Elliott Whitehead last Sunday, Croker played a key role in Manly's brave 14-6 win. The triumph is considered one of the best in club history.

The Sea Eagles lost centre Brad Parker with concussion in the fourth minute and had to play the last 28 minutes without Trbojevic after he suffered another hamstring injury.  

Trbojevic and Walker are both expected to be sidelined for about six weeks.

"It breaks my heart for those guys because they have worked really hard," Croker said. "I spent a lot of time with Turbo in rehab last year and watching it again on the replay it is really upsetting, not just for the team but for him personally.

"It is heartbreaking for Walks too because I have seen how hard he has worked in the pre-season and learning to be a half as well."

Every try from round 6

Croker required three stitches after a head clash with winger Tevita Funa but ignored the blood streaming from the wound to make a try-saving tackle on Nick Cotric moments after taking the field.

He combined with Trbojevic to lay on a try for Funa just before halftime and the Sea Eagles hung on to win.

"A few of the older boys got us in and said this is going to be one of the best wins we are going to be a part of," he said.

"That was mentioned a couple of times and again when Turbo went down. It was really special and I was just proud to be a part of it. Now it's just about getting my body ready and building into this week."