A controversial disallowed Patrick Ah Van try was the pivotal moment in Vikings' defeat by Challenge Cup semi final opponents Castleford.
Vikings had clawed themselves back into the game after giving the visitors an 18-0 start after some sloppy defence.
But tries from Paddy Flynn and a blockbuster from Danny Galea, converted by Danny Tickle made it game on again.
But a smart chip over from Marc Sneyd, created the opportunity for the on-song Michael Shenton to cross to make it 22-12 at half time.
But Widnes started the second half brighter and were rewarded with a superbly finished try when Rhys Hanbury threaded his way through, before launching Ah Van on a run to the corner.
The try took some scoring and the flankman held off Luke Dorn well to touch down.
And just before the hour mark the big wing was over again after a storming length of the field run under the sticks.
That would have levelled it at 22 apiece, but alas the touch judge intervened to indicate offside and to the dismay of the home support the try was chalked off.
From there Widnes fell away with the Tigers rattling in a series of long distance scores with Daryl Clark completing a hat-trick and Shenton grabbing his second.
Vikings had the last word, with Jon Clarke and Dave Allen sending Chris Dean in for a consolation score.
The result will have no bearing on the big game in a month's time - but Vikings know they will have to get a real grip on nippy nine Daryl Clark if they are to be measured up for Wembley suits.