The Betfred Super League fixture between Catalans Dragons and Leeds in Perpignan on Saturday has been postponed after the Covid-19 outbreak in the Rhinos camp worsened.
Leeds' home game against St Helens last Friday was called off after two players returned positive tests and a number of others were forced to isolate.
Another four players tested positive by the end of the week and, after two more rounds of testing, the club have revealed the number of positives has now gone up to eight.
That meant another postponement and the Rugby Football League's multiple cases group has extended the closure of Leeds' training ground for another five days, until a further round of PCR tests on Saturday.
The Rhinos, who also cancelled their scheduled away game against the Catalans in 2020, say they had just 14 players available last week.
The news is a body blow to the Dragons, who had been given the go-ahead to host 5,000 fans this week, compared to just 1,000 for each of their two previous home games, following an easing of lockdown restrictions in France.
The clubs are likely to be given permission to play the fixture on the weekend of the Challenge Cup final on July 17 but that will be of little consolation to coach Steve McNamara, whose side have made their best-ever start to a Super League season and top the table with eight wins from their opening nine matches.
The French club secured a television deal with broadcaster beIN Sports at the start of the season and Saturday's game was also due to be shown live in the UK on Sky.
Leeds pulled out of their trip to Perpignan last March because forward Joe Greenwood, who was on loan from Wigan at the time, had shown Covid-19 symptoms, although he subsequently tested negative.
After initially warning that the Rhinos could face sanctions for not fulfilling the fixture, RFL chief executive Ralph Rimmer said no action would be taken because of the "exceptional circumstances".
The RFL ruled the game should be re-arranged but it became one of several fixtures to fall by the wayside as the impact of the pandemic continued right to the end of the season, with final positions determined by win percentages.
Huddersfield, whose fixture against Wigan last Friday was also postponed due to an outbreak of Covid-19, have resumed training this week and say Friday's home game against Salford will go ahead.
St Helens Women's Super League game against York on Sunday is also set to go ahead after they were cleared to resume training this week following the postponement of the derby fixture with Wigan.
