Barcelona star Lionel Messi has become a father for the first time after girlfriend Antonella Roccuzzo gave birth to a baby boy whom they named Thiago.

Messi, 25, was excused from training on Friday morning ahead of the match against Celta Vigo on Saturday to attend his son's birth at a hospital in Barcelona.

"Today I am the happiest man in the world, my son was born and thanks to God for this gift!" Messi wrote on Facebook. "Thanks to my family for the support! A hug to everyone."

Argentine team-mate Sergio Aguero, who Messi said would get his vote for the FIFA Ballon d'Or behind Xavi and Andres Iniesta, wrote on Twitter: "Welcome, Thiago!! Just one thing: I'll get you the shirt of the Argentinean national team. Congrats, Leo!!!"

Iniesta added: "Many congratulations to Leo and Antonella! Congrats... I'm very happy everything turned out fine!!"

While Barca president Sandro Rosell said: "Best wishes to Leo, Antonella and Thiago. Many congratulations!"

Messi scored his 300th career goal last weekend - the second of his brace against Rayo Vallecano - and is favourite to once again claim the FIFA Ballon d'Or prize for 2012.