Newcastle's NRL finals aspirations have been boosted with the news that influential halfback Jarrod Mullen's knee injury is not as serious as first feared.

Scans have revealed the 22-year-old playmaker tore the anterior ligament in his left knee in the early stages of the Knights' 23-4 win over Canberra on Saturday, but Mullen is confident he will be back playing within four weeks.

"I have torn the anterior ligament pretty much off the bone, and partially tore the syndesmosis, which is pretty good, because had I torn that as well, then I would be out for the season," Mullen said.

"I will just rest up now and see how it goes."

Mullen will spend the next two weeks wearing an air boot to assist his recovery and said he will not make the mistake of coming back too soon.

"I thought in the back of my mind when I did it, that might be the season for me, but I will be fresh and ready to come back in four weeks' time leading into the semis," he said.

"I will getting back as soon as I can to help the boys, but I have to be cautious and make sure I do not come back to soon so I don't end up tearing it again."

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