Player welfare rules could prevent England’s best players from featuring in the Champions Cup next season, according to Exeter boss Rob Baxter.
European games will be played straight after the international windows in a bid to catch up the rugby calendar after the coronavirus break.
But players require periods of rest and clubs may have to use European games.
“We’re just in an impossible position with the Covid-19 scenario,” Chiefs director of rugby Baxter said.
“It’s just the way it drops in there immediately post-international blocks is tough.”
Next season’s competition will see the top eight sides from the Premiership, Pro14 and France’s Top 14 divided into two pools of 12, with clubs playing four pool games against sides from leagues other than their own.
The top four sides in each pool will advance to two-legged quarter-finals before a one-legged semi-final.
“It’s tough to see it as an absolute frontline competition for English Premiership clubs because you’re going to get your players back from their first block of internationals and if they’re going to play in it they play the next weekend in your first European game,” Baxter added.
“You get them back from the Six Nations and they’re straight into a European game.
“Somewhere in between all that, between coming back from the early winter internationals and the Six Nations, you’ve got to try and fit two or three rest weekends in as well for your EPS [Elite Player Squad] players.
“I think four of the fixtures are European and three are Premiership, so the whole make up of the season and how you fight your way through it is going to be a whole new interesting concept.
“I think the make up of the competition is fine, I have no problems with it for one season.
“But it’s going to be how you reincorporate your players into a team that’s capable of winning big games is going to be the interesting factor for all the coaching staff.”