Messi was on hand to double Barca's lead on the quarter-hour mark after playing Alba into space, who in turn charged down the wing and played the ball back into the path of the Argentine, who duly drilled home.
"It's a luxury to have him here". Having been teed-up by Alba for both his goals, the five-time FIFA Player of the Year returned the favour in the 28th minute with a lovely curling pass and the attacking full-back got to the ball before Sergio to prod it into the net.
Valverde said: "We are going to wait, people appreciate him a lot for the time he has been here".
A last-ditch block denied Iniesta a goal after he was set up by a delightful back-heel by Messi.More news: Scientists find thick sheets of ice just below Mars' surface
"It's incredible how he reads the game".
"We were able to both score and assist, and he is the best in the world by far, the best in history, and enjoyed by all the Catalans". "I hope that our connection continues like this forever!"
Celta coach Juan Carlos Unzue - Luis Enrique's assistant at Barca for the past three seasons - lamented his side's inability to shut down a partnership which has been so lethal this season.
With the side of his boot, Alba directed the flawless bouncing ball across the edge of the box for Messi to smash past the goalkeeper with his first touch.More news: Buy tickets - Tickets - The North American Bitcoin Conference
Modest La Liga outfit Leganes will face their mighty city rivals Real in their first appearance in the Copa del Rey quarter-finals in their 89-year existence.
The visitors failed to pitch up in the first half and they were duly punished by Barca, who were out of sight at the half-time whistle.
"We are seeing a lot of them this season, but it makes sense because there is no winger on the left anymore and there is room for [Alba] to surprise from deep".
Ivan Rakitic headed the fifth goal late in the game to round off the five-star performance of Ernesto Varvelde's side.More news: Kerber wins Sydney title in ideal start to 2018
"I would say I'd prefer not to draw Real Madrid", Valverde admitted in his news conference after the game. "We are all suffering from the derby loss", Correa said.