\"Today I am the happiest man in the world, my son was born and thanks to God for this gift!\" Messi wrote on Facebook.
Barcelona: Lionel Messi's girlfriend gave birth to a baby boy, the Barcelona star's first child, on Friday.
Messi and his girlfriend Antonella Rocuzzo named the boy Thiago.
"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."
Barcelona excused the 25-year-old Argentina forward from training Friday morning to attend his son's birth at a hospital in Barcelona.
In a recent interview with Spanish newspaper El Pais, Messi said he was looking forward to becoming a father.
"I'm prepared for Thiago's arrival, it is very exciting," said Messi. "It makes you think of things in a different way. You can no longer just think about yourself, you think about him, and how you hope he doesn't have any problems."
Earlier Friday, Barcelona coach Tito Vilanova said he still expected Messi to play in Saturday's Spanish league match against Celta Vigo at Camp Nou stadium.
"Leo didn't attend training, but tomorrow he will play in the match," said Vilanova. "If everything goes well, he will come to play. It doesn't change our plans at all that he didn't train today."
Thiago's birth was reported by various Spanish news outlets, and Messi's father, Jorge, told Argentine news agency Telam that he had been born.