They have competed for accolades at club level, international level, and at individual level.
While Messi has stayed at Barca for his entire career, Ronaldo has played for four teams in his career, which means there is an interesting crew now known as the 'Messi-Ronaldo club'.
These are players who have been a team-mate of both superstars:
Team-mates of Lionel Messi and Cristiano Ronaldo
Gabriel Heinze, Ezequiel Garay, Gerard Pique, Nelson Semedo
The first player to have the honour of playing with both Messi and Ronaldo was Gabriel Heinze, who was an Argentina international while playing with CR7 at Manchester United.
Heinze's compatriot, Ezequiel Garay, naturally played wth Messi at international level, while he was Ronaldo's team-mate at Real Madrid between 2008 and 2011.
Conversely, Nelson Semedo is an international colleague of Ronaldo with Portugal, but played with Messi at Barca.
One player that people tend to forget is on the list is Gerard Pique. The Spaniard is so synonymous with Barcelona that his time at Manchester United is almost lost in the memory. He remains the only player in history to have won the Champions League with both Ronaldo and Messi.
Fernando Gago, Deco, Andre Gomes, Arthur, Miralem Pjanic
For Messi, his Barca team-mates Deco and Andre Gomes are compatriots of Ronaldo.
It wasn't a typical swap deal as fees were exchanged (€60m for Pjanic, €72m for Arthur).
Both made their debuts on the same night for their new clubs this past Sunday and subsequently became the 13th and 14th players in history to join the Messi-Ronaldo club.
As the Bosnian made his debut later on in the evening, he is the latest member of the club.
Carlos Tevez, Gonzalo Higuain, Angel Di Maria, Paulo Dybala, Henrik Larsson
There is a major Argentine flavour to the forward that have played with both Messi and Ronaldo.
Messi has only played with 4/5 players at national team level.
Higuain would go on to partner Ronaldo at Juventus, too.