Hull's top-four hopes suffered a jolt with a shock 42-16 defeat at bottom side Widnes.
The Vikings, who had lost three games in a row, led 20-10 at half-time with full-back Shaun Briscoe turning in a top show against his old club.
He scored two of Widnes' eight tries as his side fought back from a 10-8 deficit midway through the first half.
Willie Isa also crossed twice for the Vikings with Paddy Flynn, Frankie Winterstein, Danny Craven and Rhys Hanbury adding four-pointers.
Jordan Turner, Joe Westerman and AaronHeremaia got Hull's tries.
- Shaun Briscoe