Newcastle Knights second-rower Dylan Lucas is in line for a remarkable return in the club's sudden death semi-final against the New Zealand Warriors next weekend.

The Knights, missing Lucas, Dylan Brown and Jacob Saifiti were able to knock over the South Sydney Rabbitohs on Friday evening in the opening match of the finals.

The upset win extends their season in to Week 2 of the finals, and the Knights, who have played well above their expectations all year, will be hit by a major boost, with Lucas to return per The Newcastle Herald.

The forward suffered an ankle fracture and dislocation during a Round 21 match against the Parramatta Eels. Dylan Brown was injured in the same game, with the Knights then hanging on to qualify for the finals in seventh spot.

It's understood he will only be named in the extended squad, but will then be assessed during the week with a view of flying to Auckland with the Knights when they jet out later in the week.

In a surprise boost, the Knights have also been locked in to play on Sunday, giving Lucas more time to recover by 24 or potentially 48 hours.

The second-rower may well only come off the bench if he does return given the form of current second-rowers Francis Manuleleua and Jermaine McEwen, who have been excellent since Lucas was injured.

The NRL Physio, speaking on the injury through his social media accounts, said the eight-week return to play would be a record timeline from an ankle fracture in dislocation - the previous being Aidan Guerra's effort to come back in ten weeks during 2019.

The Knights will clash with the Warriors next weekend at Eden Park.