Ozil and Ronaldo played together for a number of years at Madrid before the Germany playmaker’s big-money transfer to Arsenal in the summer of 2013.
Ronaldo has recently become Real Madrid’s all-time top goal-scorer and has been in fine form this season.
And the Arsenal playmaker was quick to send a message to his former team-mate on Instagram on Friday afternoon.
Ozil shared the picture above of the duo playing for Real Madrid on the photo-sharing app and wrote: “Happy Birthday, my friend! #RealMadrid #oldtimes #cr7 #cristiano #ronaldo”
Ozil, 27, will be expecting to feature when Arsenal return to Premier League action with a trip to Bournemouth on Sunday afternoon.
The World Cup winner was unable to help Arsene Wenger’s men conjure a winner as they were held to a frustrating goalless draw by Southampton at The Emirates on Tuesday night.
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news