The Super League match between Wakefield Trinity and Leeds Rhinos has been postponed after two players tested positive for coronavirus.
Wakefield confirmed on Tuesday two of their players had returned positive results and the rest of the squad will have further tests in 48 hours. One of the players was involved in last week's game against Warrington Wolves.
Thursday's other matches, Hull KR versus Wigan Warriors and Salford Red Devils against Castleford Tigers, will still go ahead.
Huddersfield Giants will play St Helens and Warrington will face Hull FC as planned on Friday, despite six of the Wolves' playing squad being required to self-isolate for 14 days due to Wakefield's positive tests.
Rugby Football League (RFL) chief regulatory officer Karen Moorhouse said in a statement: "In what are unprecedented and uniquely challenging circumstances for the sport, we should first recognise the importance of the health and well-being of the players and other staff, and their families, at the clubs who have been affected.
"Again, we have been forced as a sport to show our ability to move quickly to ensure we still have a programme of four attractive fixtures in the Super League – and again, we are grateful to the flexibility of the clubs involved, and of our broadcast partners, in agreeing to these changes at such short notice."