When Barcelona went 1-0 down to Valencia in the 60th minute on Sunday, the Blaugrana must have feared they were about to suffer their first defeat of the season.

Nothing was working for Ernesto Valverde's team, who were dominant at the Mestalla Stadium, and it required a moment of magic from Lionel Messi to level the scores.

In the 82nd minute, Messi dropped into the No.10 and clipped an inch-perfect pass into the box for Jordi Alba, who volleyed home with aplomb.

The game ended 1-1, meaning Barcelona maintained their unbeaten run and four-point lead at the top of La Liga.

But all three points should have gone to the away side after Messi was denied a clear goal in the 30th minute, when his shot squirmed past Neto and over the line.

Every player and fan at the Mestalla could see it was a goal, yet neither the linesman nor the referee gave it and play resumed.

Barcelona's players were furious, especially Messi, and even Valencia captain Dani Parejo admitted after the game that the ball was over the line.

"Messi's goal was clear. It was a clear goal, truth has to be told. Referees make mistakes," said the Spanish midfielder.

New footage has now emerged of Messi reacting to his ghost goal being disallowed and Mundo Deportivo claim to know what he said to the linesman and referee afterwards.

Check out the video below.

MESSI SLAMS THE LINESMAN & REFEREE

According to Mundo, Messi told them both after the game: "You're wrong, now you're going to see it," to which the linesman replied: "It is not clear."

The referee then added: "As I'm not sure, it's not a goal."

VAR (video assistant referee) hasn't yet been introduced in Spain but following the injustice at the Mestalla, La Liga officials are making sure it arrives next season.

Messi's disallowed goal could prove costly in the title race and even though Barcelona are still clear at the top of La Liga, the difference two points makes cannot be overstated.