Barcelona have completed a domestic double by defeating Athletic Bilbao 3-1 in the Copa del Rey final, with Neymar finding the net in between a Lionel Messi brace.

There were half chances for both sides in the opening stages as the match began in lively fashion, with a disallowed Barca goal among the early talking points.

Neymar was on hand to volley a Messi cross into the net with 10 minutes on the clock, but Bilbao were saved by the linesman's flag.

It was goalkeeper Iago Herrerin who came to their rescue moments later when Ivan Rakitic slid a pass through to Luis Suarez, with the Bilbao stopper making himself big to deny the Uruguayan from close range.

Messi broke the deadlock for Barca in the 20th minute with a strike that was remarkable even by his own lofty standards. The Argentine beat five Bilbao players before rifling an unstoppable shot into the bottom corner.

Neymar was a constant thorn in Bilbao's side, and he doubled the La Liga champions' lead in the 36th minute, bundling the ball over the line from close range following good link-up play between Rakitic and Suarez.

Bilbao posed little threat to the Barca goal in the first period, but did hit the crossbar moments before half time as Andoni Iraola picked out Inaki Williams and the midfielder let fly.

Barca could have been out of sight on the stroke of half time, but Herrerin produced an acrobatic save to keep out Messi's curling effort, giving his side hope of salvaging something in the second period.

Bilbao looked tighter after the break, and the Catalans had another chance to kill the game off in the 57th minute as Suarez pounced on a loose ball in the box, only to be denied by a last-ditch challenge from Xabier Etxeitia.

Although Ernesto Valverde's side saw more of the ball in the second half, they still struggled to create anything in the final third and it was only a matter of time before the champions put the game to bed.

Messi drove the final nail into the Basque club's coffin in the 74th minute, poking home a Dani Alves cross from close range following poor defending from Bilbao.

Williams was Bilbao's standout performer, and he got his name on the scoresheet late on, heading Ibai Gomez's cross into the bottom corner to pull a goal back with 10 minutes remaining.

Tensions boiled over in the dying stages as the Bilbao players reacted angrily to some perceived showboating from Neymar, adding colour to an otherwise low-tempo conclusion, although Xavi did rattle the post with a free kick in stoppage time.

Barca's cup triumph puts them in contention for a treble this season, with Luis Enrique's side due to face Juventus in the Champions League final on June 6.