New Doncaster RLFC head coach Richard Horne failed to celebrate his first game in charge with a win in Sunday’s League One 25-20 defeat at Whitehaven.
The Dons, who had been second-best to the third-placed Cumbrians for most of the game, scored three tries without reply in the final quarter only to come up just short.
With Newcastle Thunder posting a 48-12 home win over Hemel the Dons, who have a game in hand over all the sides above them, dropped to sixth with just three weeks of the regular season remaining.
With a top-four finish in the regular season ensuring four home games in the Super 8s, Horne immediately set his charges the target of four wins from their last four games in a bid to claim fourth spot – the only realistic top-four spot still up for grabs.
But the former Hull FC star knows that even an eight-point haul from their remaining games may not be good enough to prize fourth spot from York City Knights given the fact that they have a better points difference.
Knights, who opened up a two-point gap on the Dons following their win at Keighley, have a points difference of 128 compared to their 18. Newcastle (74) also have a superior points difference.
Victory for the Dons over Newcastle, who also have to visit Hunslet and entertain Coventry, on Sunday would go a long way to seeing off their top-four challenge.
York entertain struggling Hemel Stags and Workington Town, whose main target would now look to be securing their Super 8s spot, following Saturday’s visit to Canada to face unbeaten Toronto Wolfpack.
The Dons also entertain Oxford and travel to ninth-placed University of Gloucestershire and second-bottom South Wales Ironmen.