A Tom Lennon goal after 14 minutes helped Roscommon to the narrowest of wins in a keenly contested match at Cloone.
Roscommon led 1-6 to 0-5 at half-time and a converted Derek Duggan free after the restart stretched their advantage even further before Leitrim enjoyed their best spell, scoring four points without reply to leave just a point between the sides by the three quarter mark.
Emmet Sweeney grabbed the crucial point for the winners after 17 minutes of the second half. Duggan added another a few minutes later, but Leitrim rallied, and points from the inspirational Declan Darcy and from Aidan Rooney meant the narrowest of margins divided the teams at full time.