Barcelona boss Luis Enrique compared Espanyol's roughhouse tactics to the NFL after the visitors had two men sent-off in the second bad-tempered Catalan derby in four days as Barca came from behind to win 4-1 in the Copa del Rey on Wednesday.

Hernan Perez and Papakouli Diop were shown red cards in a four-minute spell in the second-half with Barca already leading 3-1 thanks to a Lionel Messi double.

Messi then teed up Neymar for a stunning fourth to all but seal Barca's place in the quarter-finals ahead of the second leg on January 13.

Espanyol's intense approach had worked in frustrating Barca with a 0-0 draw on Saturday.

Yet, they lost their discipline completely in the final quarter with goalkeeper Pau Lopez escaping punishment for a blatant stamp on Messi.

And there were reports that the players from the two sides even came to blows in the tunnel after the game.

"The referees are the ones to set the limits. They are responsible for ensuring this is football and not American football," said Enrique.

"Anything that takes us away from football worries me. All we are looking for is to play.

"When someone goes beyond the limit with their actions, there is a referee there (to act).

"We are teams used to playing in our own way and we have to understand that in a positive light."

Felipe Caicedo had put Espanyol into a shock lead before Messi replied four minutes later.

A wonderful Messi free-kick just before half-time put Barca in front before the Argentine provided two fine assists for Gerard Pique and Neymar to put the tie beyond Espanyol's reach.

And Pique admitted Messi had been the key to opening up the visitors.

"Derbies are always intense and they have a way of playing on the limit. There are referees that allow it like the other day and referees that don't like today," said the Spanish international.

"Their plan is to play very tough and they made sure we didn't have fluidity in our play.

"Leo helped us a lot with the first two goals to open the game up and then we took advantage to create more chances and score the third."

However, Espanyol captain Javi Lopez claimed the negative media attention given to his side after Saturday's stalemate had influenced the referee.

"I like to define us more as an intense team," he told Canal Plus.

"We are proud of the team, we are very intense and they lacked respect for us calling us violent. We are hurt with how they have us treated during the week.

"The media campaign we have suffered since the league game has taken effect."