Sydney Roosters prop Dylan Napa has waved a red rag in front of Jason Taumalolo by describing him as the key to beating the Cowboys.

Heading into Saturday’s NRL grand final qualifier, Napa’s assessment of the Roosters’ opposition was simple – stop Taumalolo and stop the Cowboys.

However that’s been easier said than done this year.

After making 230-plus metres in back-to-back finals matches, the Cowboys talisman leads the league for running metres with a daunting 4707m.

Before last week’s semi-final, Parramatta publicly challenged Taumalolo to step up to the mark and the reigning Dally M medallist responded with a game-changing 230m effort.

It led Cowboys coach Paul Green to warn rival sides not to poke the bear but regardless, Napa has laid down the gauntlet.

While he said the Cowboys weren’t a one-man band, he said so much of their creativity came off the back of Taumalolo’s work through the middle.

“I think he’s the key, he’s their go-forward,” Napa told AAP.

“Jake Granville is quick out of dummy-half and Michael Morgan plays off the back of it.

“We definitely won’t be solely concentrating on one player but it’s been pretty clear all year he’s a star and he’s a beast.”

So how do you stop an irresistible force such as Taumalolo?

According to Napa, you can’t, you just limit the damage.

Last time they met, the Roosters targeted him however he still carved out 206m in the Roosters’ 22-16 round 21 win.

“He won the Dally M last year and he’s probably improved,” Napa said.

“I think Jason’s one of those players you can’t really stop, you can only contain.”