The attacking side should always score. For a period last night, in an actual match situation, Hull KR were able to extend that to 13 v 11, in theory gaining an even greater chance of success.However, given the countless and utterly bizarre ways in which they managed to somehow ruin continuous try-scoring opportunities – in what should have been a time of rich harvest – you wonder if Tim Sheens’s side would even have scored if the equation was 13 v 9.They had 15 minutes to score against an outnumbered Warrington Wolves who were down to 12 men, then reduced to 11 and then back up to 12 during a chaotic period in the first half yet could not muster a single point.It was embarrassing to watch as the befuddled hosts – camped on their opponents’ line continuously for at least eight successive sets – almost aimlessly set about their work. Warrington could not believe their luck and duly gleefully claimed their place in the Coral Challenge Cup semi-finals even if Rovers eventually fought back to leave it remarkably tense at the end.Steve Price’s side had been 22-0 ahead after Ben Murdoch-Masila blasted over for their fourth try in the 52nd minute.Inevitably, though, when playing such long periods under-manned, that added defensive slog eventually has to catch up with you.Rovers duly responded with three tries in 15 minutes as Josh Drinkwater’s brace after a crafty ball-steal and 60m sprint from Ben Crooks, with two Ryan Shaw conversions, saw them back to just 22-16.But Wolves stand-off Blake Austin, like he so often does, came up with a big play straight after to ease nerves and send Ben Currie over meaning Craig Hall’s solo try at the death was too little, too late.Unfortunately, then, all Rovers now have to look forward to is a likely relegation fight.The visitors led just 6-0 when they saw their first player sent to the sin-bin in the 20th minute.Given he used to play for Hull FC, Tom Lineham was predictably booed all the way down the touchline after he was yellow-carded for a late hit on Jimmy Keinhorst.Keinhorst had flicked a pass onto Crooks, the winger who would likely have scored if he had headed directly for the corner but, instead, cut inside to a swathe of defenders.It was a first sign of that debilitating hesitancy from his team.That said, credit Warrington as well and, in particular Currie, who produced two try-saving tackles in quick succession to somehow deny George Lawler - who was over the line - and then Keinhorst.But, during this period, the Super League high-fliers’ discipline also continued to wane and they were put on a team warning following yet another penalty.That meant, when KR prop Mitch Garbutt drove close and earned a quick play-the-ball, Dec Patton was sin-binned as he dragged a burrowing Danny Addy down from an offside position.Rovers surely had to score now but McGuire, of all people, inexplicably kicked early in the tackle count, his effort miscuing and sailing over Crooks’s head into touch.McGuire did set Drinkwater into space and then ran on the last as well to set Hall free but Addy fumbled going over the line.When Lineham was restored, the hosts still had chances but one by one they were frittered away as the ineptness continued.Warrington’s effort was magnificent but they were out on their feet.Still, almost inevitably, when back up to 13 and despite having barely been out of their half, they somehow managed to muster enough energy to score a second try with the final play of the half.Bryson Goodwin summoned up some strength to brush off McGuire and Austin popped up to score on his inside, Patton making it 12-0.When Mose Masoe fumbled with no one near him at the start of the second period, you sensed the interval had served Rovers no good whatsoever either.Instead, Lineham smuggled over in the corner far too easily and Warrington – whose first score had come via Jake Mamo – should have been home and hosed when Murdoch-Masila barged over. But Rovers flickered into life. At last. And all too briefly.Hull KR: Hall; Crooks, Keinhorst, Linnett, Shaw; Drinkwater, McGuire; Maria, Addy, Masoe, Lawler, Hauraki, Mulhern. Substitutes: Atkin, Garbutt, Lannon, Harrison.Warrington Wolves: Mamo; Charnley, King, Goodwin, Lineham; Austin, Patton; Hill, D Clark, Cooper, Currie, Hughes, Philbin. Substitutes: J Clark, Murdoch-Masila, Akauol, Davis.Referee: Robert Hicks (Oldham).