Louth fell to their first league defeat in over 12 months as their defence was dismantled by Roscommon's double spearheaded attack of Frankie Dolan and Stephen Lohan.
Between them, Dolan and Lohan scored all but one of their side's scores, with all 1-7 of Dolan's total coming from placed balls.
The two crucial scores - a goal for each - came within a minute of each other nine minutes into the second half. First Lohan was hauled to the ground by Louth full back Denis Reilly for a penalty which Dolan hammered to the net.
A minute later, Louth pushed the self-destruct button. Though a shot by Dolan was parried by goalkeeper John Nally, Lohan collected the rebound to score.
Louth might have snatched a draw at the death, but substitute Aidan O'Neill's low shot hit the side-netting at the near post.
ROSCOMMON: S Curran; D Gavin, K Keane, J White; G Mockler, M Ryan, P Noone; F O'Donnell, D Connellan; C Connelly, F Grehan, G Cox; N Dineen, S Lohan, (1-3), F Dolan (1-7, one pen, five frees, two 45s). Subs: D Kelly for D Connellan (35 mins), L Dowd (0-1) for C Connelly (61 mins), C McDonald for M Ryan (61), R O'Callaghan for F O'Donnell (71).
LOUTH: C Nally; B Philips, D Reilly, B Reilly; S Gerard (0-1), S Melia, J Neary; S O'Hanlon (0-1), M Farrelly (0-4); C Grimes (1-1), C O'Hanlon, M Stanfield (0-2, two frees); D Reilly (0-2), D Kirwan, J P Rooney. Subs: A O'Neill for D Kirwan (43 mins), A Hoey for J Neary (48 mins), P McGuigan for C O'Hanlon (63 mins).
Referee: J McKee (Armagh).
