Hull coach Lee Radford and Danny Houghton both admitted their disappointment as the Airlie Birds failed to strengthen their play-off berth over the weekend.
They went down 44-22 at home to Salford in a result that blows the race for the top five wide open, when a win would have lifted Hull up to second.
Houghton said: “We have put ourselves in a dogfight for the top five.
“It looks a little bit like knockout football for seven weeks now. We have got to treat every game as a Grand Final or a semi-final. We need to string a run of six or seven games together.”
Dubbed inconsistent for much of the year, Hull had the chance to leapfrog Warrington following their defeat to Wigan on Friday.
But a defeat now boxes up the six teams chasing the four play-off spots beneath St Helens, with Salford now heavily fancied to finish in the top five.
Catalans defeat at home to London has hit their hopes, though Castleford eased past relegation haunted Huddersfield on Sunday.
Radford added: “With a game of that magnitude – we could have secured top five tonight – to turn up with that attitude, I can’t tell you how disappointed I am with some of the blokes.
“They need to understand what tonight was. Now we play knockout football. One more individual has an off night we don’t get a second bite at the the cherry. Tonight was that insurance that maybe we could have an off night.”