FREMANTLE ruckman Jon Griffin says he is pleased star Aaron Sandilands has signed on for 2017 and believes the veteran's presence continues to drive him to get better.

Griffin, 30, has had an indifferent season so far. He played in round one but was dropped for rounds two and three.

He has reclaimed the No.1 ruck role while Sandilands has been recovering from the serious rib and lung injury suffered in round three.

It has been a battle for Griffin to gain opportunities since joining the Dockers from Adelaide via a trade at the end of 2010. 

He played 41 games in four seasons at the Crows but he has played 42 games into his fifth season with Fremantle, 10 of those alongside Sandilands. The rest have come while the four-time All Australian has been out injured. Griffin also missed 12 months due to a knee reconstruction in 2013.

Match preview: Fremantle v Richmond

Griffin signed a contract extension until the end of 2017. Sandilands also re-signed last month but Griffin said he was not concerned about what that could mean for his opportunities next year.

"To have him sign is great for the footy club, it's awesome," Griffin said on Wednesday. 

"To have that competition within the club obviously drives me to get better and to become a stronger player. I love having Aaron around."

Sandilands is still at least two to three weeks away from returning from injury. Griffin said the pair could play in the same side but he said that decision was out of his hands.

"The only thing I can control is my form," Griffin said.

"That's up to the match committee. I think we played a handful of games together during the end of last year. I love playing footy with him." 

Griffin said he had been leaning on Sandilands for advice in preparing for the opposition ruckman each week.

He had to play as the sole ruckman against Greater Western Sydney in round seven, with support from key defender Zac Dawson. But Zac Clarke shared the duties with Griffin last week against Hawthorn. He said the ruck combinations depended on the opposition the Dockers faced.

Clarke is out of contract at the end of this season and is set to become an unrestricted free agent.