Mayo completely obliterated Roscommon in McHale Park on Sunday, hitting three goals in a devastating first-half display.

The power and destruction of Mayo's opening period was the complete winning of the game and very little happened in the second half, such was the profound nature of that initial showing.

Connacht SFC Semi-Final:
Mayo 3-18 Roscommon 0-7

John O'Mahony's side had things wrapped up shortly after the restart, Aidan Kilcoyne hitting the first goal and Pat Harte's penalty more or less sealing things soon after.

The third goal came when Aidan O'Shea smashed to the net and the Mayo supremacy was consummate and total.

Mayo led by 17 points at half-time and the second half was sedate and dull as they wound down their performance into one of containment.

Roscommon for their part continued to fight and managed to keep the second-half scoreline relatively tight and respectable.

However, there was no arguing with the final margin as Mayo progressed to the provincial final with remarkable ease.

It's not often a Championship game is won within the first 15 minutes but that's exactly how it was in Castlebar.

Mayo nicked the first point through a Kilcoyne free and then he grabbed the first goal of the game with a low, slotted finish under the keeper after good work by O'Shea.

Alan Dillon hit four points in the first half and he made it 1-2 to nothing before Kilcoyne added another. That put Mayo six up and the game had hardly started.

Any threat of Roscommon mounting a recovery was ruthlessly denied on 12 minutes when Mayo hit their second goal through Harte's sublimely taken penalty.

Kilcoyne took his own tally to 1-3 with a fine score and Dillon made it 2-5 to 0-0 shortly afterwards.

It was harrowing stuff from a Roscommon perspective, and when Paul Kelly's point-blank goal effort was saved by Mayo's Kenneth O'Malley, things appeared to have taken on an almost tragic perspective.

Mayo continued to tip scores over and got their third goal of the game when O'Shea sailed onto Dillon's pass and cracked a glorious finish past Geoffrey Claffey. That left 16 points as the gap.

Mayo's main ploy was the long ball into their tall full-forward line, and it was devastating the visitors. However, their technical executions were faultless too.

Conor Devaney got Roscommon's sole first-half score through a well taken free but efforts from Ronan McGarrity, Dillon and Peadar Gardiner made it 3-10 to 0-1 at half-time. It was a royal hammering.

Thankfully, Roscommon got the first point of the second half through a second Devaney free but Mayo wing-back Andy Moran quickly popped one over in response.

Mayo were showing no signs of reducing their workload, and their technical mastery of proceedings was not diminishing either, exemplified by a majestic, curling point from McGarrity.

Pat Harte and Brian Higgins traded points then, but Mayo were insanely far in front and the match was growing increasingly dull and patternless.

Nonetheless, both sides continued to go through the motions, Mayo hitting points through Gardiner, Mortimer and the excellent Dillon.

Roscommon's consolation scores before the end came from a Donal Shine free, a brace from wing-forward Gary Cox and a fine effort from Karel Mannion, but to say it mattered little is quite the understatement.