The champions cannot be beaten

Defeat in the first leg had shown a certain element of weakness from Barcelona, showing they were in fact beatable. And Espanyol fancied their chances of progressing into the semi-finals.

You may be able to stop Barcelona once, but it's almost impossible to do it twice. A defensive layout from Quique Sanchez Flores, who admittedly was tactically spot on in his team's 1-0 win at Cornella, was almost immediately dismantled by the hosts.

Urged on by the Camp Nou faithful, whose disapproving whistles and jeers resounded around the stadium with every decision which went against Barcelona's interests, Lionel Messi began to exploit the spaces in the final third.

With Espanyol camped inside their own half, it was only a matter of time before speedy interplay from the hosts saw the ball hit the back of the net. After nine minutes, the tie was level, Aleix Vidal serving the cross for Luis Suarez to nod past Pau Lopez from six yards.

The visitors were unresponsive. When Barcelona are in the mood, there is little you can do. And, orchestrated by Messi, the hosts were certainly up to the task. They dominated possession and pushed Espanyol further into their own half.

After 25 minutes, Barcelona doubled their lead. It was vintage Messi as he ran across the edge of the area before firing a low shot which deflected off Naldo and wrong-footed Lopez on its way in.

As the minutes went by, Espanyol looked increasingly vulnerable, with Barcelona unwilling to let up. They almost put the tie out of reach for the visitors with Messi and Suarez failing to double their tally but, when the referee blew for half time, Espanyol remained a goal away from qualifying for the next round.

Right down to the very end there was a growing fear inside the Camp Nou that Espanyol could stun the hosts late on, despite an utterly dominant display that failed to find its reward in the second half. Espanyol came out holding a higher line after the break which put some distance between their defensive third and Barca's forward, but it did not stop the hosts from keeping the ball as well as they did in the first half.

With the clock ticking, the away side were forced to take more chances and go forward, which eventually opened up spaces for Barcelona, who somehow failed to put the game to bed. Messi, who ran proceedings in the Catalan derby, unleashed a shot that fizzed inches wide of the post before he cannoned a header off the Espanyol post. The game was destined to go right down to the wire.

Arguably the highlight of the second period came when Andres Iniesta was replaced by new signing Philippe Coutinho, with the crowd on their feet to welcome the Brazilian. He was quick to get involved in the action against his former club, squaring the ball for Suarez to fire straight at Lopez, who quickly got to his feet to deny Ivan Rakitic.

Valverde will be content with the way Coutinho linked up with his new team-mates and will be overjoyed to have sealed their berth in the Copa del Rey semi-final after a fixture that should have ended comfortably for the La Liga pacesetters. For now, they cannot be stopped.