RICHMOND premiership pair Shaun Grigg and Josh Caddy will remain on the sidelines for some time, with no clear return date set for the duo.

Grigg has been dealing with a knee complaint for at least a month, while Caddy has had an ankle issue for a similar period of time.

FULL INJURY LIST Who's racing the clock for round one?

"Grigg's injury has been a little bit vague, we've had a little bit of progress this week," Richmond's physical performance manager Peter Burge told richmondfc.com.au.

"He's had about four or five scans in the last couple of weeks, different methods to try and work out what the problem is, and we seem to have narrowed it down.

"He had some treatment this week which he's responded really well to. He's been running for the past five weeks or so, but he just hasn't been able to train at a high intensity.

"We think now in the next week we'll be able to progress that [and] hopefully from there we'll have a bit more of an idea of when he might return to football training."

Caddy has started running after nearly three weeks out with his ankle injury.

"We probably have to extend the timeframe a little bit with reconditioning and then back into the football program," Burge said.

"So, he's probably about a week away from resuming some skill work and then we have to make an assessment as to what that looks like with match play."

Star recruit Tom Lynch remains touch and go as to whether he plays round one.

The key forward didn't play any JLT Community Series matches as he recovers from a long-term PCL injury.

"Tom's been in full training with the group now for probably nearly two weeks [and] he's been in the skills program for five to six weeks," Burge said.

"He's going fantastically well, even the session yesterday (Thursday) he looked pretty good. It's a long-term injury so we're obviously taking a very measured approach.

"He is getting closer, but that's going to be a decision between the medical and coaching team. Hopefully over the next week we'll be able to enlighten some people with that news."

Premiership forwards Jason Castagna (ankle), Jacob Townsend (stress reaction in his femur) and key back Ryan Garthwaite (Achilles tendonitis) are set to return on managed minutes in a VFL practice match against Northern Blues next Thursday afternoon.