Worcester Warriors are to meet fellow Championship side Doncaster in the British & Irish Cup final.
Doncaster will host the game at Castle Park on Good Friday (3 April) after Saturday's shock 27-22 semi-final victory at home to the Warriors' Championship promotion rivals Bristol.
Worcester came from behind to win 15-13 against Leinster A on Friday night.
Victory for Dean Ryan's Warriors denied the holders their chance of keeping the trophy for a third year.
Loose forward Mat Gilbert and full-back Perry Humphreys both scored tries as Warriors came from behind to book their place in next month's final.
It took 28 minutes for either side to break the deadlock before Cathal Marsh landed the first of his two first-half penalties, but Worcester led 7-6 at the break when Tiff Eden converted Gilbert's late first-half try.
Humphreys stretched Worcester's lead when he galloped clear to score and, although Andy Symons missed the kick, he then landed a late penalty to take his side two scores clear at 15-6.
Centre Noel Reid crossed for Leinster in the final minute. But, although the conversion by visiting stand-off Marsh edged the Irish side back to within two points, Worcester ran down the clock to hang on for their narrowest win of the campaign.
Worcester's club-record 24th straight victory in all competitions looked likely to set up another meeting with Bristol ahead of the much-anticipated final-day league meeting between the Championship's top two teams at Sixways on 18 April.
But Doncaster had other ideas, beating Bristol on Saturday afternoon thanks to tries from prop Richard List, number eight Ollie Steadman and captain Michael Hills.
Worcester: Humphreys; Smith, Grove, Fatiaki, Biggs; Eden, Bruzulier, Fainga'anuku, Sowrey, Rees, Percival, D Sanderson, Cox, Gilbert, de Carpentier.
Replacements: George, Bower, Daniels, Taylor, Arr, Symons, Hammond.
Leinster A: Kelleher; Coghlan-Murray, Te'o, Reid, M McGrath; Marsh, L McGrath; Dooley, Dundon, Burke-Flynn, Molony, Denton, Marshall, Leavy, Timmins.
Replacements: B Byrne, Hirst, Beirne, Coghlan, Rock, Crosbie, O'Shea.