Plymouth Argyle's Championship survival prospects suffered a damaging blow as they were beaten 3-0 at Swansea City.

Plymouth were outplayed and outfought by a Swansea side who seized the early initiative through Lewis O'Brien's diving header and never looked like losing from that point on.

Harry Darling then headed in at a set-piece before Josh Key's stunning long-range strike sealed a comprehensive victory after only 35 minutes.

Plymouth's best effort was a second-half header from Jordan Houghton which was saved, but in truth Argyle were fortunate not to be on the end of an even heavier beating as the hosts dominated.

Abject defeat in a game boss Miron Muslic had suggested his side must win means Plymouth stay bottom of the table, five points adrift of safety with only five games remaining this season.

With some testing fixtures still to come, the Pilgrims must finish a difficult campaign in spectacular fashion if they are to avoid a return to League One after two seasons in the second tier.

Swansea have had relegation concerns, too, though their Championship status looks all but secured courtesy of this victory.

Alan Sheehan's team have moved up to 14th in the table, nine points clear of the drop zone.

For caretaker head coach Sheehan, it is now 14 points from eight matches in what has been an impressive spell since the departure of Luke Williams in February.

Plymouth have had some torrid times on their travels in the league this season, winning just once and scoring only eight goals.

They had shown signs of life on the road in recent weeks, with victory at Portsmouth followed by a draw at Watford, but were second best from the outset against Swansea at a point in the season when much better was required.

After a gruelling weekend win over Derby County, the Swans enjoyed being given time and space to play.

Their opening goal came inside four minutes, on-loan Nottingham Forest midfielder O'Brien scoring his first for the club as he met Ronald's measured cross with an equally sweet finish.

Darling then strolled into space to nod Eom Ji-Sung's left-wing free-kick inside the far post before Key stretched the advantage, the right-back unleashing a dipping 30-yard shot which sailed beyond Conor Hazard.

Goncalo Franco had a long-range volley saved, while Zan Vipotnik wasted a fine chance as he blazed over with Plymouth reeling.

The visitors had only one effort before the break, an Adam Randell free-kick which was pawed to safety by Lawrence Vigouroux, but their performance was desperate.

Muslic responded by making three half-time changes, with one of the new faces, Houghton, drawing a decent save from Vigouroux with a header which was almost his first touch.

But in truth, nothing much changed.

Swansea ought to have stretched their lead when Vipotnik shot over from six yards – and the opportunities kept coming against the leakiest defence in the top four divisions.

Eom's header forced a sprawling Hazard stop before the South Korean wasted a glaring opportunity as he slashed over.

There was still time for Vipotnik to miss another chance as Plymouth avoided a humiliation – but the result piled more pressure on Muslic's team.

Swansea City interim boss Alan Sheehan:

"I'm delighted. That's one of our best performances, we went after them really, really early.

"I thought we just dictated the game from start to finish. It's as complete as you can potentially hope for. On another day we could have scored a few more goals if we'd been more clinical.

"But in of attitude, application and quality tonight in the right areas, playing the right way, I'm really happy with that.

"We wanted to put on a show. We understood how dangerous this game was - they have just beaten Norwich - but we wanted to match their intensity and bring it all together tonight.

"Some of our play was top, top level."

Plymouth Argyle head coach Miron Muslic:

"[On Saturday] we had a strong team performance. Every time we have an opportunity to move closer and take big step, we can't.

"Every time we prepare to make the next step after a good performance, we disappear.

"That's why disappointed and that's why we are in the situation we are in. Every opponent is capable of realising the moment and every time we have the chance to do this we simply give it away.

"It's getting even tougher but we had same pressure against Norwich last week and we did it well. I know the difficulty of this task but it's possible."