Krisnan Inu started his Canterbury career with a bang as he inspired his new club to a 30-12 win over Sydney Roosters on Monday night at the Sydney Football Stadium.

The mercurial former Parramatta utility back signed for the Bulldogs last Thursday from the Warriors and made an immediate impression, scoring two tries, setting up a third and kicking three goals as the Roosters slumped to a third successive defeat.

Des Hasler's side sealed the win on the back of some outstanding defence, soaking up intense pressure from the hosts in either half, but taking advantage when in possession to run in six tries.

Hasler was full of praise for Inu and said he was delighted to have secured the services of a player of his calibre mid-season.

"He's played in two grand finals and lots of Test footy and he is a handy acquisition for us given the extent of injuries we've had to our inside backs," he said.

Roosters coach Brian Smith said his players appeared to run out of energy midway through the second half, and skipper Anasta revealed his frustrations at another refereeing controversy, when the visitors led 14-12.

Anasta said referee Jason Robinson apologised to him late in the game, admitting he bungled a call that led to Canterbury's third try.

Anasta argued that Lafai should have been penalised for a knock-on, in the build up to the try, but was waved away by Robinson.

"He told me he didn't see it," Anasta said.

"It didn't cost us the game but it's so frustrating as it keeps happening to us.

"He then comes to me at 30-12 and says 'sorry Braith I got that one wrong'."

"It's too late then."

The Roosters broke the deadlock in the ninth minute when Mitchell Pearce stepped off his right foot to slalom his way under the posts for his third try of the season.

The Bulldogs' response was swift as they took full advantage of a penalty conceded by Boyd Cordner to find good field position three minutes later, and Inu scored an easy try in his 100th career game.

Sam Kasiano looked to have given the Bulldogs the lead when he charged to the line, but the big New Zealander was ruled to have impeded two players and the try was ruled out by the video referee.

To add insult to injury for the visitors, the Roosters responded when Anthony Minichiello darted over and Braith Anasta added the extras.

However, the Bulldogs scored two quick tries just before the interval with Inu brilliantly catching and offloading in mid-air for Frank Pritchard to crash over.

And from the following set, Jonathan Wright latched onto Michael Ennis's hopeful kick forward and touched down.

The Roosters started the second half well but the Bulldogs took control by the 56th minute with Inu darting over from dummy-half for his second four-pointer.

David Stagg then touched down for his side's fourth try just after the hour-mark, and Wright iced the game with a breakaway run from 90 metres after Anasta's intended pass for Mitch Aubusson fell into his hands.

The Dogs (14 points, +87) jump from eighth to fifth on the ladder, the 18-point margin pushing them past the Cowboys (14, +78) on for-and-against.

Manly and Wests Tigers also have 14 competition points but the Warriors are nipping at their heels in ninth.

Bulldogs: 30 (K Inu 2, J Wright 2, F Pritchard, D Stagg tries; K Inu 3/6 conversions)

Roosters: 12 (M Pearce, A Minichiello tries; B Anasta 2/2 conversions)

ABC/AAP