Canberra have boosted their NRL finals hopes after easily overcoming a lacklustre Sydney Roosters outfit 34-12 at Canberra Stadium.

Two tries each to centres Joel Monaghan and Marshall Chalk helped the Raiders to another upset win with much of the game played under steady rain.

The triumph lifted Canberra to ninth, just one point behind eighth-placed Penrith, and follows last week's unexpected victory over St George Illawarra.

Raiders mentor Neil Henry admitted it was a satisfying win, especially after Sydney's 30-4 destruction of Canberra back in round nine.

"The boys are starting to get a little bit of consistency about what they're doing," Henry said.

"It's a big game for us. They (Sydney) have been very good for most of the year."

For the Roosters it was a second consecutive loss but if coach Brad Fittler was worried, he wasn't showing it.

"The result doesn't really matter," Fittler said.

"What it means is that we did a good job earlier in the year (and) that puts us in a position to lose a couple."

Fittler, whose team were also upset by the Gold Coast at home last week, praised the opposition.

"We knew it was going to be tough. Their last five games have been excellent," he said.

"They play with a great attitude. They've got all the qualities of a good side."

Canberra's first try came in just the sixth minute through five-eighth Terry Campese, who was on the end of a slick backline movement.

Two more tries before the break meant the one-time wooden spoon favourites led their much-fancied rivals 18-0.

The scoreline did not tell the story of 40 minutes of brisk and largely mistake-free football from both sides.

Superb kicking games were on display through Raiders half Todd Carney and Roosters playmaker Braith Anasta.

But Carney took the points from their duel, choosing to start kicking long once the rain began falling.

"When the wet weather football comes in it's definitely something you start thinking about," Carney told AAP.

The Roosters managed to cross the line twice in the second half, but the Raiders had all the answers in the 22-point win.

Before the game Henry had admitted the game plan was to run outside the Roosters' compressed defence. It was a plan that worked.

"You get a long kick in and you want to see the chase," Carney said.

"We've been priding ourself on our kick chase.

"Today our last passes stuck."

The Raiders now need to keep winning and will face a tough challenge at home to the Titans in round 20.

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