Derrell Olpherts scored four tries as Castleford produced a stunning second-half performance to blow Hull FC off the park and claim a vital two points against their closest rivals for the top six.
It was also a dream return for Lee Radford, facing his former club for the first time at the MKM Stadium.
Both sides came into the game in play-off positions, with a win for either going a long way to boosting their post-season hopes and the game was finely poised at half-time, with Hull battling back from eight points down to take a slender lead into the break.
However, after the restart, the home side collapsed, with Castleford registering six second-half tries without reply, four of which whilst having a player in the sin bin, to claim a 46-18 win.
The visitors made a great start and, after an early Danny Richardson penalty, scored the first try through Olpherts, who collected Greg Eden’s deft kick with no one around him to touch down for a converted try.
Eden was then penalised for taking Connor Wynne out going for a Jake Connor kick and the resulting melee saw Olpherts and Wynne sent to the sin bin.
However, from the resulting penalty, Hull got themselves on the board through Mitieli Vulikijapani, who crashed through the Castleford line after a great right to left shift from the hosts.
Hull then grabbed their second try in dramatic fashion. A kick from Connor looked to have evaded Darnell McIntosh, but the winger did exceptionally well to ground the ball barely inches from the dead ball line to give Hull the lead.
Suddenly it was all Hull and they scored for a third time, with Danny Houghton catching the Tigers out on the back of a penalty and raced 40 metres untouched to score under the posts.
Castleford had the final say of the half as Olpherts grabbed his second, carrying three Hull defenders over the line in the left corner and Richardson converted to cut the gap to four at the break.
HT: Hull 18-14 Castleford Tigers
The Tigers went down to 12 men shortly after half-time when Jake Mamo was sin binned but it did anything but hinder the visitors, who went on to hit Hull with four tries in a devastating spell whilst he was off the field.
Bureta Faraimo scored twice in two minutes and Olpherts completed his hat-trick either side of a Suaia Matagi try as the Tigers ran riot on both edges despite being down a man.
Frustrations boiled over for Hull, with Wynne being sin binned again for a melee in back play and Hull were down to 11 men when Ligi Sao was sent off for a high shot on Mamo to compound the home side’s misery.
There was no response from the home side as Olpherts grabbed his fourth, with Alex Sutcliffe rounding out the scoring for the Tigers as they claimed a priceless win in the race for the play-offs.