Ellis played a key role in the Mustangs making last year's Waratah Champions League semi-finals and re-signing him for 2020 is a priority.

"We're still talking to Isaiah, obviously we want him back. He is a big priority of what we're trying to do as we had such a good year with him last year," Mustangs coach Luke Boyle said.

"Our biggest problem at the moment is that he is playing in Switzerland and we've just got to work out his transfer dates.

"We need to make some decisions by probably early February because we have to get someone over here or locked in.

"We are looking at another guy who we are trying to secure, but again we've got to make sure it's right for the team and the board's position as well.

"There are a couple of people who we are keeping our eye on to fill that other spot.

"It's an added expense and we need to our work on the sponsorship side of things as well."

The Mustangs will retain the majority of last year's squad with the exception of James McAnulty, Jason Duerden, Andrew Hodge and Lachlan Beavis, who has moved to Melbourne.

They returned to training last week and Boyle is excited about the development of key juniors Taiga Cantor and Riley Markovich.

"We've got a pretty decent squad of guys. We had a few fellas who finished up with us but the good thing is we've got a whole bunch of young kids who are coming through as well," Boyle said.

"It was good to see where everyone was at, because I think to be honest we are a lot fitter than where we were at the same stage last season.

"Some of the young guys are starting to fill out which will allow them to step up even further.

"Riley Markovich has put on a whole lot of weight since last year. He is really only a young kid but he is going at it pretty hard at training and he is definitely holding his own.

"Then you have the likes of Taiga, who is overseas at the moment but looked like he had filled out more. Once they've been in the senior team one or two years you usually start to see a bit more maturity as well."

Cantor had a break-out season in the youth team, stepping up in the absence of Dan Millburn who played Championship Men.

"We want to get one or two new guys into the rotation so that over the years they become the senior guys.

"Guys like Taiga are certainly at the top of the list to blood them and give them more opportunity."

The competition is set to resume mid-March.