Struggling Brisbane veterans Jack Gunston and Daniel Rich have been left out of the Lions team to play Sydney on Friday night.

Coach Chris Fagan made the announcement at his Thursday morning press conference, saying both players had approached him on Monday morning to discuss their form.

They will now enter a "training block", although the exact period of time is yet to be determined.

Fagan said he hoped the move was a circuit-breaker and was confident the pair could return to the senior team later in the season.

"They're not happy with the way that they're playing at the moment, they believe their form doesn't warrant selection," Fagan said.

"There's obviously the option to go back and play in the reserves, but at their age, I think the best thing we can do for them, to give them the best chance to get back to playing their best, is to give them a training block.

"For the next weeks that's what they'll be doing, building their bodies up, building their fitness up.

"I'm not sure how long they'll be out for and when they'll be ready to come back, but that's the decision we've made."

Rich has played seven games this season, missing time with quad and calf injuries, and has struggled defensively while battling to make his usual impact with ball-in-hand.

Gunston has kicked 11 goals in 11 games. He has been goalless in the past two Brisbane losses to Adelaide and Hawthorn, gathering just five and six disposals respectively.

"When you see the team tonight they'll be out managed, one of the great words that has just appeared in AFL footy in recent times," Fagan said.

"Both those guys are champion footballers. 

"You want to give them a bit of time to get back to playing their best football, but they recognised it themselves this week.

"I'm very confident those boys will get back and play some good footy."

Dayne Zorko is due to return from a one-match suspension against the Swans, but after taking minimal part in Tuesday's training session, Fagan did not confirm his inclusion.