Cristiano Ronaldo and Conor McGregor square off ahead of UFC 202

Ronaldo is a friend of John Kavanagh, McGregor's trainer

McGregor and Ronaldo stare each other down in the Octagon (Instagram / @cristiano)

Cristiano Ronaldo stepped into the Octagon for the first time on Sunday to visit Conor McGregor in Las Vegas.

The Portugal international is holidaying in the United States following his success at this summer’s European Championships.

McGregor, meanwhile, is preparing for next month’s UFC 202 event, when he will seek revenge against Nate Diaz, who defeated him at UFC 196.

The featherweight champion was unbeaten under the UFC banner prior to the Diaz bout in March, which ended with McGregor tapping out of a rear naked choke.

Ronaldo, who is friends with McGregor’s trainer John Kavanagh, posted a picture of the pair squaring off to his official Instagram account with the caption: “Great to see you bro!!”

“My brother Ronaldo dropped by the gym today!” McGregor wrote on his own Instagram.

“He is an animal. Thank you @cristiano, much respect! I will see you for that Forbes number 1 spot next year. #ThisIsTheMacLife,” he added.

Ronaldo was named the highest-paid athlete in the world by Forbes magazine earlier this year, with his salary estimated at $88m (£67m) per annum.

McGregor, meanwhile, became the first MMA fighter to be included, with his earning estimated at $22m, the 85th-highest.

Ronaldo is still recovering from a knee injury sustained during the first half of Portugal’s extra-time win over France in the Euros final at the Stade de France.

The Real Madrid forward is expected to miss the start of the club season, with a return pencilled in for the home clash against Osasuna on 11 September.