The home side looked to be in the driving seat when they surged 1-8 to 0-7 clear in the 46th minute. But they failed to score again and were reduced to 14 men when centre-forward Declan Nolan received a straight red card.
Inspired by the excellent Keith Higgins, who ended up with 0-10 overall, the visitors reeled in the home side and it was only a matter a time before they hit the front.
Roscommon started brightly and were helped by Gerry Fallon’s 11th minute goal from a 13m free. Higgins and Cathal Freeman kept Mayo in touch but points from Declan Nolan (two) and a 70m free from ShaneCurley left Roscommon 1-6 to 0-5 ahead at the break.
The advantage was still four points 11 minutes into the second-half but the wheels came spectacularly off the Roscommon bandwagon after that.
Scorers for Mayo: K Higgins 0-10 (4fs), C Freeman 0-4, C McCrudden, K Feeney 0-1 each.
Scorers for Roscommon: D Nolan 0-3, Gerry Fallon 1-0f, Gary Fallon 0-2fs, S Curley (f), T Seale, J Coyne 0-1 each.
MAYO: D O’Brien; S Connell, P Connell, A Brennan; G Henry, A Connolly, S Morley; K Higgins, D McConn; P O’Grady, C Freeman, C McCrudden; D McDonnell, S Hoban, B Hunt.
Subs: K Feeney for McDonnell (46), S Markham for O’Grady (65).
ROSCOMMON: D Dowd; S Curley, P Kelly, D Fallon; S Melia, S McDermott, N Keenan; D Flaherty; B Donnelly; J Lawlor, D Nolan, Gary Fallon; T Seale, Gerry Fallon, J Coyne.
Subs: K Conneely for Flaherty (32), M Kelly for McDermott (ht), E Mulry for Gerry Fallon (51), E Kenny for Gary Fallon (51), A Moore for Seale (65).
Referee: C Browne (Galway).