Sale Sharks' final Gallagher Premiership match against Worcester Warriors has been postponed until Wednesday after the club reported a number of COVID-19 positive tests, the league announced on Saturday.
The Premiership also said that the match between Gloucester Rugby and Northampton Saints was cancelled due to a number of Saints players having to self-isolate after playing Sharks earlier this week.
Sharks had initially said that Sunday's match would go ahead while Warriors, who said all their tests were negative, released a contrasting statement that the match was "still the subject of discussions" before the Premiership stepped in.
The Premiership carried out an "urgent review" and a contact tracing program along with Public Health England and the local health authorities before deciding to postpone the match.
"In light of the unprecedented situation facing Premiership Rugby we have been forced to postpone the match," the Premiership's chief executive Darren Childs said in a statement.
"Our priority is the health and well-being of everyone involved, and we won't compromise this. But as this match has such a critical bearing on deciding the Premiership Rugby champions, we wanted to do everything we could to play it."
The Sharks are fourth in the table and forfeiting the game would have seen them lose out on a playoff spot, with fifth-placed Bristol Bears also on 64 points ahead of their final match against the London Irish.
Childs added that the match would only go ahead after an additional round of testing at Sale on Tuesday and both teams will not be allowed to register new players with the Rugby Football Union prior to the game.
The Premiership added that Saints had informed them on Friday that they did not have enough front row players to fulfil the fixture.
As a result of the cancellation, eighth-placed Gloucester were awarded a 20-0 victory and five points.
"We understand and fully sympathise with Northampton Saints' position," Childs added. "They are in this position due to no fault of their own, but unfortunately they cannot fulfil the fixture."
The Premiership season, which was suspended in March due to the pandemic, restarted in August and the remaining final round matches will be played on Sunday with all matches kicking off simultaneously.