Dewsbury Celtic suffered a 38-10 defeat to National Conference Division Two leaders Millom.
Pat Foulstone scored a try and goal for Celtic, whose other score came from Thomas Halloran.
Millom ran in six tries from Tom Sibley (four), Ricky Donoghue, Steve Dawson, Warwick Carter, Anthony Green and Marcus O’Brien with Adam Kelly adding five conversions.
Millom have won all 12 matches this season and are four points clear of nearest challengers Featherstone Lions, while Celtic drop back to eighth place.
The welcome second placed Featherstone to Crow Nest Park on Saturday (ko 2.30pm).