Castleford may be forced to postpone Thursday's Super League derby with Leeds after being hit by coronavirus.
The Tigers say three players have tested positive for Covid-19 and are self-isolating in line with Government regulations.
With a further six ruled out as part of track and trace and another 11 injured, Castleford coach Daryl Powell says he has just 14 players available but will check on three more on Thursday morning before making a final decision on the game.
Rules introduced since the start of the pandemic state a club can postpone a fixture if seven or more players are unavailable for 'Covid-related reasons'.
"We've up to 20 players unavailable for various reasons, which is unprecedented across rugby league I think," Powell said in a zoom press conference on Wednesday afternoon.
"It's really rattled us as a group. We're in a bit of trouble here, obviously with Covid and we've got a significant number of players who are injured.
"We've got 14 fit players and three who will be looked at in the morning who are real doubts. In a normal week, they wouldn't play. It's a really tough situation to be in.
"Obviously we want to play the game. We've had to do all sorts of things to keep our season going and have just got on with it.
"How this is going to pan out in the morning I just don't know. Clearly we can't go into a game with 14 players.
"It looks an impossible task at the moment, but we're leaving it as late as possible."
Powell was forced to scrap training on Wednesday and Leeds coach Richard Agar says his club's preparations were also disrupted.
Three players from the Rhinos' last opponents, Wigan, have tested positive this week and Agar was forced to hastily put back Wednesday's captain's run by an hour as he waited for re-tests after some initial ones proved inconclusive.
"Thankfully everybody has been cleared," said Agar.
Wigan will go ahead with Friday's game against Warrington and Powell says it is crucial clubs play to a conclusion this season.
"I think it's really important that we get through the season," he said. "It's going to be tough.
"Obviously the Challenge Cup final is in a couple of weeks' time, so that will be one of the competitions that come to a conclusion and then it's getting through the rest of it and getting the Grand Final played.
"We've just got to act tough. To scrap the season would be disastrous, I'd hate to see that.
"We've got to battle through. Rugby league is a tough sport played by tough people from generally working-class areas where they want to see this, they want to see sport.
"As difficult as it is, we have to get through. I just don't think we should be thinking about quitting. We don't quit in rugby league, we crack on as much as we can until it's an impossible situation.
"It may come to that, I don't know, but until there is no other option, I think we need to keep going."
