Hull returned to the Premier League on Saturday by clinching a runner-up finish in England's second tier ahead of Watford on a dramatic final day of missed penalties, late goals and high tension.
After missing and then conceding a converted penalty in injury time to draw 2-2 with already-promoted Cardiff, Hull would have been denied the other automatic promotion place in the League Championship if Watford had beaten Leeds.
However, Watford conceded a late goal because of an error by its substitute goalkeeper to lose 2-1 and finish two points behind Hull. Watford's match ended late because of a lengthy first-half injury delay, with Hull forced to wait to learn its fate.
"I have been around the block but I don't think I have ever witnessed anything like that,'' said Hull manager Steve Bruce, who used to play for Manchester United.
"It's put us through the ringer... It's just totally ridiculous.''
Watford, who are managed by former Italy and Chelsea forward Gianfranco Zola, still has a chance to go up via the playoffs that will also feature Brighton, Crystal Palace and Leicester.
Hull of a show
Hull came from behind to take a 2-1 lead and was then awarded a penalty in the third minute of added time that sparked a mini pitch invasion by fans who thought the referee had blown for fulltime. Once the crowd had cleared the field of play, Nick Proschwitz stepped up but saw his penalty saved.
Cardiff then launched an attack and Hull defender Abdoulaye Faye was adjudged to have handled the ball, allowing Nicky Maynard to convert in the fifth minute of stoppage time.
"I thought we were in the playoffs. You couldn't have written the script better"
Hull defender Paul McShane
"I thought when they scored the penalty, it was all over,'' Hull defender Paul McShane said.
"I thought we were in the playoffs. You couldn't have written the script better.''
Watford needed to better Hull's result but was handed a major blow when goalkeeper Jonathan Bond was carried off on a stretcher in the first half after colliding with teammate Ikechi Anya. Bond was only playing after an injury to first-choice Manuel Almunia in the warm-up.
That meant inexperienced third-choice goalkeeper Jack Bonham came on but he crashed into his own player to allow Leeds to take the lead. Almen Abdi equalised for Watford but Bonham's day got worse when he fumbled a shot by Ross McCormack and saw the ball dribble into the net in the 90th minute.
Hull was relegated from the Premier League in 2010 after a two-year stay.
The club is owned by Egyptian-born businessman Assem Allan, following his takeover in December 2010.
Cardiff had already secured promotion to the Premier League as champions.