Newcastle coach Nathan Brown will face the first major test of his depth this weekend when the Knights take on St George Illawarra Dragons without injured five-eighth Connor Watson.

While the choice of replacement was an easy one for Brown, it has forced him to restructure the side both in terms of personnel and game style.

"Brock [Lamb] is totally a different type of player to Connor," Brown said.

"We certainly need to look at what Brock's skill-set is. I suppose there's a few little adaptions as a team we will make to suit Brock.

"If he's not hungry or keen in the coming weeks I'd be very surprised and very disappointed, to be honest with you."

Teenage fullback Kalyn Ponga also admits his role is likely to be different due to Watson spending the next six weeks on the sidelines with a shoulder injury.

"I'll probably look to vary it around as we have different personnel in there," Ponga said. "So, I might shift around a bit."

The former Cowboy has been explosive for his new club, averaging more than 100m running in his three Telstra Premiership matches.

Newcastle fullback Kalyn Ponga. ©NRL Photos

With Watson missing, Ponga can now be more versatile and operate on either side of the ruck. He is looking forward to the challenges that await him from the red-hot Dragons at WIN Stadium on Sunday.

"I know [Matt] Dufty at the back is pretty sharp and he's a very good player," Ponga told NRL.com.

Ponga said the Knights learned a valuable lesson against the Roosters last weekend. 

"As a group we identified what went wrong and it was plenty of effort errors," Ponga said.

Dragons v Knights: Lamb replaces Watson, Dragons unchanged

"But that's easily fixed. We will rebuild, and we will be better this weekend. We just didn't compete as hard as we should have."

Newcastle staff are confident Aidan Guerra will be fit to play, despite the back-rower missing training on Wednesday due to a leg injury.

As well as preparing for the Dragons, the Knights have spent the week dealing with the sacking of rising star Dylan Phythian following a second positive drug test.

While Brown has not closed the door on him returning to the club down the track, he said it would be in the best interests of the 22-year-old Belmont junior to rebuild his career elsewhere.

"There's always a door open if people are doing the right thing," Brown said.

"The club will still finance his rehabilitation which our club doesn't have to do. The club will also look to help him find work.

"But I think Phyth leaving the Knights and going to another club would probably be in his best interest in the short term anyway."