They are seen playing football and having fun in downtime playing poker with friends. At the end of one ad Neymar Jr raises the stakes, only to find out he and his opponent have the same cards.
The videos have been released on the social media site two weeks before airing on TV, globally.
Had an awesome time producing this film with @PokerStars and hanging out with a legend. #LovePoker...Foi muito divertido gravar este filme para a PokerStars e ainda por cima matar a saudade dessa "lenda". #AmoPokerPosted by Neymar Jr. on Saturday, August 1, 2015
Tarquin Henderson, the head of EMEA gaming sales at Facebook, said: "People come to Facebook to discover things that matter to them, whether it’s photos from their friends and family, videos from brands they love, or posts from their favourite celebrities.
"PokerStars’ campaign combines the best of this – fresh, engaging content from two of the biggest footballers on the planet.
"And thanks to Facebook’s scale and unparalleled targeting tools, these videos will reach the most relevant audience, from poker and gaming fans to football aficionados."
The ads have been produced by Vaughan Arnell, the commercial and music video director.
Michael Hazel, the interim chief executive at Rational Group, said: "This is the biggest PokerStars marketing campaign in history and we are excited to launch with exclusive distribution on Facebook.
"Both videos show how each of the stars love the game of poker in their own unique way."