Manly have all but secured a top four NRL finals berth thanks to a player who couldn't run without three injections to his knee before kick-off.

Yet there were no signs of any lag from Anthony Watmough during his side's 36-22 win over Canberra at Canberra Stadium.

The Raiders threatened to miraculously chase down the Sea Eagles late in the match until a 53rd minute Watmough try snuffed out those ambitions.

But the 30-year-old representative star only forced himself out onto the field in the first place due to injuries to fellow key players Brent Kite and Brett Stewart.

"I didn't run until Thursday - tried to run and couldn't," Watmough said.

"I went and saw the doc. Two or three locals in the knee to get out there was what it took and lucky enough it worked.

"Ideally you don't like doing it. With the people we had out today, it was a sacrifice we had to do."

In order for Manly to now drop out of the top four they'd have to lose their last two games and the Sharks would have to win their remaining three.

"Maybe, if we can seal a top four, I can get a week off if (coach Geoff Toovey) will allow it," Watmough said tongue-in-cheek while sitting next to his coach.

"But I love playing week-in, week-out, and I'll be fighting him if he tries to give me a week off."

Watmough's knee injury was caused by a controversial leg twist from South Sydney forward Jeff Lima last week.

Watmough admitted displeasure at the tackle, but avoided weighing in to whether Lima should have copped more than a one week ban.

"That's in the past. I wasn't happy at the time, but it's done and dusted now," he said.

"He just stirred up a bit of soft tissue damage and I don't think your leg is meant to bend that way but that's in the past now.

"I'm not the law maker, we're the ones copping it but we have to deal with the decisions they make."