Courtney Hill’s superb second half try helped underdogs Leeds retain the Women’s Challenge Cup in Bolton.
The Rhinos were significant outsiders with bookmakers despite winning last year’s competition, with Castleford unbeaten this season in Super League.
But Australian Hill - a former cricketer who played alongside tennis star Ashleigh Barty in the T20 - supported a brilliant break from Danielle Anderson to finish a length of the field try.
And Leeds - coached by Rhinos first team player Adam Cuthbertson - held on in the final quarter to lift the trophy.
Much of the pre-match attention had focused on Castleford winger Hollie Dodd, who made her debut just a day after turning 16.
Dodd coped well with the step up from junior rugby and had an intriguing battle with opposite number Fran Goldthorpe, also just 16.
An absorbing first half finished with the sides level at 10-10.
The Tigers opened the scoring with a rampaging 45-metre try from loose forward Rhiannon Marshall, who was only cleared to play in the game the week before after successfully reducing a suspension.
But the Rhinos responded with two tries in six minutes.
First Goldthorp out-jumped Dodd to take a Hill kick to score, before full-back Caitlin Beevers got on the outside of the Castleford defence directly from a scrum.
The Tigers were level at the break when Tamzin Renouf took a Claire Garner pass to power over by the posts, and a tight contest played out after the restart.
The deadlock was broken just before the hour mark in what proved to be the game’s decisive play.
From a scrum deep inside their own half, Rhinos prop Anderson burst the defensive line and timed her pass to the supporting Hill perfectly for the scrum-half to race clear and score.
Castleford asked plenty of questions of the Leeds defence in the closing stages, but the Rhinos stood firm, bundling full-back Tara Stanley into touch in the closest they came to forcing golden point extra-time.
