Friday’s Super League fixture between Huddersfield and Castleford has been cancelled after Tigers revealed 12 positive Covid-19 tests.
Castleford’s tests took place on Tuesday, 27 October.
Super League and RFL will make another announcement “as soon as practicable”.
The postponement follows the cancellation of Monday’s match between Catalans and Warrington, which was called off because of a spike in Covid-19 cases at the French club.
Leeds, who beat Castleford on Monday night before Tigers were tested on Tuesday, are scheduled to play Wakefield Trinity on Thursday.
Further results of this week’s testing programme at all clubs will be provided as soon as complete information is available.