The referee's performance was the big talking point as Leitrim overcame 13-man Clare in Carrick-on-Shannon.
Shaun McLaughlin of Donegal showed eight players from each team the yellow card and straight reds to Gordon Kelly and David Tubridy.
Leitrim should have had a healthier lead at the break after Clare captain Gordon Kelly's dismissal in the 29th minute, but a series of missed frees kept Clare in touch 0-6 to 0-4.
Two unanswered Clare points immediately on the resumption restored parity, but the visitors were reduced to 13 men in the 40th minute when centre-half forward David Tubridy saw red.
Clare led by two points with four minutes left, but in a frenetic finale Leitrim sub Conor Beirne struck two points and Wayne McKeon broke banner hearts with the winner.
SCORERS -- Leitrim: J Glancy 0-4 (1f), C Beirne 0-3 (3f), A Croal 0-2, R Cox, R Mulvey, W McKeon 0-1 each. Clare: A Clohessy (2f), D Tubridy (2f) 0-3 each, R Donnelly 0-2, C O'Connor, S Brennan, G Brennan 0-1 each.
LEITRIM -- C McCrann; G Reynolds, R Gallagher, P Maguire; D Beck, B McWeeney, B Prior; T Beirne, W McKeon; R Mulvey, J Glancy (capt), P Brennan; B McDonald, A Croal, R Cox. Subs: C Beirne for R Cox, C Maguire for R Mulvey, C Clarke for P Brennan, C Sheridan for G Reynolds, D Sweeney for B McDonald.
CLARE -- J Hayes; L Healy, B Duggan, N White; M McMahon, G Kelly (capt), J Hayes; G Brennan, C O'Connor; D Daly, D Tubridy, N Browne; R Donnelly, T Ryan, A Clohessy. Subs: S Brennan for T Ryan, K Hartnett for N White, M Foran for D Daly, S McNelis for M McMahon.
REF -- S McLaughlin(Donegal).