Pau Lopez should have been third Espanyol player to see red after stamping on Lionel Messi during 4-1 Copa del Rey defeat

Espanyol goalkeeper Pau Lopez stamped on Lionel Messi's right ankle as tensions frayed during Barcelona's 4-1 win at the Nou Camp.

The visitors ended a bad-tempered game with nine men after Hernan Perez and Papakouli Diop were sent off, but Pau could have joined them too after this altercation with the Barcelona star.

The Espanyol man was already angry before half-time, clashing with Arda Turan and Luis Suarez after the Turkish midfielder came close to knocking the shot stopper's head with his boot while challenging for a loose ball.

Espanyol goalkeeper Pau Lopez (right) appeared to stamp on Lionel Messi's right ankle during the match

Lopez could have been sent off for the moment of madness which saw him lash out at Barca's Messi

The Espanyol custodian (far right) exchanges words with Luis Suarez during the match at the Nou Camp

Both Suarez and Pau were booked by referee Martinez Munuera, who struggled to control the game, showing his yellow card to six Espanyol and four Barcelona players.

Soon in the second half, after Messi and Gerard Pique scored either side of the interval to put Barcelona 3-1 up, he appeared to attack the Argentine forward.

In the 54th minute while getting up off the floor, Pau stepped on Messi's ankle and then instead of stopping continued the motion with more force, using it as a platform to stand up on.

Messi was furious and squared up to the goalkeeper, with Suarez acting as a peacemaker on this occasion.

Diop, who was sent off for saying something to Suarez which the referee did not like, hit out after the game.

'You cannot say we were violent. There wasn't any blood. If we had wanted to be, the Barcelona players would have gone off on stretchers.'

Meanwhile, Espanyol defender Javi Lopez insisted his team had not mistreated Barcelona.

Lopez (left) also did not look like he was too happy with Barcelona debutant Arda Turan on Wednesday night

Espanyol defender Javi Lopez (left) keeps a close eye on Neymar (right) during the feisty cup clash

After the 0-0 draw in La Liga between these sides on Saturday, many Barcelona media sources focused on Espanyol's aggression, ahead of this Copa del Rey last 16 clash.

Lopez said: 'I like the word intense to define us. In the first half with 11, Barcelona didn't want to put the ball out when [Felipe] Caicedo was on the ground. Barcelona didn't put the ball out.

'We are proud of the team. They lacked respect by calling us violent, we are very hurt by how they have treated us during the whole week.

'In no moment of the league game did we act violently. Watch the game again. The media campaign since the league game has had its effect.' 

Messi was the architect of Barcelona's latest victory, scoring two goals and claiming two assists

Gerard Pique rushes straight to Messi to celebrate after the mercurial forward set up the centre back

Neymar capped an excellent evening for Barcelona, scoring their fourth with an excellent volley