Fremantle coach Ross Lyon faces a real headache in the ruck department, according to former Docker Paul Hasleby.

Hasleby's concerns center around the impressive form young ruckman Sean Darcy displayed towards the end of last season, with the returning Aaron Sandilands expected to be fit for round one.

Two bonafide ruckman are rarely selected in the same side in the modern game, with neither Darcy nor Sandilands proven forwards it presents a dilemma for the Fremantle match committee.

“I wouldn’t (play both). I don’t think they can,” Hasleby told SEN’s KB and The Doc.

“I think we saw last year that to play two giant ruckmen like that who haven’t established themselves as forwards in their own career (isn't effective).

"Sandilands has tried but has sort of failed as a forward throughout his career and Darcy is a bit the same.

“They are going to have to go with one or the other.”

Hasleby was impressed by Darcy's debut season, in which the big man averaged 34 hitouts and 12.2 disposals across eight games, but still believes Lyon will opt for Sandilands to begin the season.

“I like what Sean Darcy did last year,” Hasleby said.

“He’s the future of the club and he’s good at winning the tap-ups. He’s also a bit more mobile around the ground, particularly with the follow up work to put on blocks and handballs and bring his teammates into it.

“It’s going to be tough for Ross Lyon. I know Ross Lyon will go to Sandilands first, he always backs in the senior guys at the start of a season, but if it doesn’t work it will be interesting.”

Hasleby also commented on the pending return of star Eagle Nic Naitanui, expressing his concern over the ruckman's fitness, with the possibility of missing the JLT pre-season matches a strong chance.

“Going into a season proper without some practice games is a little bit concerning,” Hasleby said.

“I think he’ll play most of the year if all feels right with his knee, but can he get back to his elite best? I have my doubts for this year.”

Fremantle open their season with a stern test against Port Adelaide at Adelaide Oval.