Dewsbury travelled up to West Cumbria looking to complete the double over Whitehaven and thanks to a masterclass from Anthony Thackeray in the halves, they completed the double with a comfortable victory.
The visitors had the better of both halves and opened the scoring through Dale Morton in the 24th minute, but the home side were soon level after Declan Hulme crossed when Brett Seymour came out of the line and missed the tackle.
But Rams’ Nathan Conroy scored and restored their lead just before the half-time break.
Haven reduced the gap to two through winger Craig Calvert, but the damage was done with three second-half tries in 11 minutes.
Scott Hale, Toby Adamson and Morton’s second all looked to have finished a tired Haven side off. The home side were down to 14 players by then and Rams were taking full advantage breaking tackle after tackle. Despite that Haven grabbed a consolation try through Ben Davies as he crossed under the sticks.
But Rams wrapped it up when Joel Farrell crossed in the final minutes to seal an impressive away victory.
Whitehaven: Jouffret, Burns, Hulme, Taylor, Calvert, Aiye, Gore, Beaumont, Coyle, T. Chapelhow, Allen, McAvoy, Davies. Subs: Newton, Brooks, Ancely, Hepi.
Dewsbury: Fieldhouse, Morton, Crookes, Hale, Scott, Seymour, Thackeray, Nash, Wildie, Hepworth, L. Adamson, T. Adamson, Brown. Subs: Conroy, Farrell, Smith, Jackson.
Referee: Jamie Bloem (RFL).