Townsend has been sidelined for five weeks with a calf injury but has declared himself a certain starter for Friday's mouth-watering NRL clash against Newcastle.

The eighth-placed Sharks can leapfrog the seventh-placed Knights with a win and Townsend is under no illusions how much the game could mean to the finals hopes of both teams.

With a game against the ninth-placed Warriors the following weekend, Cronulla could all but secure a top eight spot with back-to-back wins.

"Our next two weeks are definitely going to be huge," Townsend said.

"We're coming up against the Knights who had a pretty severe loss on the weekend ... and then also a week after that, the Warriors who are playing some really good football at the moment."

Townsend's injury ended a run of over 100 straight NRL appearances for the 29-year-old, who used the layoff to get a new perspective on the game from the coach's box.

Watching his teammates alongside John Morris, Townsend says it's apparent if the Sharks can be defensively resolute they have the firepower to worry anyone in the competition.

Last Saturday's 28-12 win over North Queensland was an example of the defensive resilience Townsend wants to see from his teammates going forward.

"The boys took a really good step forward on the weekend," Townsend said.

"We know we can score points, I think we're second or third for points scored in the competition so for us it's about the defence. Defend, that's our message."

Townsend said both Jesse Ramien (eye) and Josh Dugan (knee) are expected to train on Tuesday and be fit to face the Knights.

Newcastle forward Mitch Barnett has also given himself the green light to play, despite suffering a sternum injury in last Saturday's heavy loss to the Warriors.

Barnett will play with a chest guard and pain-killing injection, for what he knows is a crucial game.

"We've got an opportunity to not only get a good result but finish the season on a high heading into semis," Barnett said.

Australian Associated Press