Castleford Tigers' Super League matches against Leeds Rhinos and Salford Red Devils have been cancelled after another four players tested positive for coronavirus.
The Tigers' clash with Huddersfield Giants last Friday was called off after testing revealed 13 players had contracted COVID-19.
Castleford will also be unable to fulfil their fixtures with the Rhinos on Friday and Salford next Monday due to another four members of their squad testing positive.
The Rugby Football League's Multiple Cases Group has extended the shutdown of the Yorkshire club following the latest positive results.
A decision over whether Castleford's scheduled round 22 encounter with Wakefield Trinity will go ahead has not yet been made, with two more rounds of testing set to be carried out this week.
The pandemic has wreaked havoc with the Super League schedule, but Catalans Dragons are back in action at Salford on Monday.