Messi's last-gasp goal marked his 500th for Barcelona and blew the La Liga title race wide open at Real Madrid on Sunday.

Victory takes Barca top of the table thanks to their better head-to-head record with both sides locked on 75 points, but Madrid have a game in hand.

"We went to the Bernabeu to win and to continue to fight for La Liga," the five-time Ballon d'Or winner said on his Facebook page.

"There is still a long way to go, but we left with the joy of having taken an important step," added Messi, the top scorer in La Liga with 31 goals, alongside a photo of himself celebrating one of his goals.

Barcelona are bidding for a third straight La Liga and Spanish Cup double. They play Alaves in the Cup final on May 27.