Rafa, Roger, Novak and Andy.

The names roll off the tongue for the modern-day tennis fan as quickly as John, Paul, George and Ringo do for a Beatles geek.

This fab four - or the Big Four as they are known - of the ATP Tour's post-millennium golden era are not seen together much these days, with Rafael Nadal becoming the third of the group to retire at the end of last year.

But he, Roger Federer, Novak Djokovic and Andy Murray reunited on Sunday as the French Open gave an emotional farewell to its 14-time champion.

"After all these years fighting for everything, it's unbelievable how time changes the perspective of things," an emotional Nadal, 37, told his rivals-turned-friends after they strode out to join him on Court Philippe Chatrier.

"All the nerves, pressure, strange feelings when you see each other when you're rivals, it's completely different when you finish your career.

"We built amazing rivalries but I think in a good way, we fought hard for titles but were good colleagues and respected one another.

"It means a lot that you're all here. I really enjoyed a lot pushing myself to the limit every single day to compete with all of you."

Federer, who famously held hands with Nadal as they cried during the final match of the 43-year-old Swiss' career, received the first warm embrace, with hugs for Djokovic and Murray following.

Djokovic, 38, arrived in Paris just hours earlier after winning the 100th title of his career on Saturday, while Briton Murray laughed afterwards he had thought he would be at the ceremony in his role as the Serb's coach.

Their partnership came to an end earlier this month, resulting in French Open tournament director Amelie Mauresmo asking 38-year-old Murray if he could still make it.

"I didn't know they would be here - but I could imagine they would come," Nadal said.

"The agendas of people sometimes are difficult. But of course they know that [being there] would make the day very special for me."

Murray travelling to Paris from London and back on Sunday was a measure of his respect and appreciation for Nadal, who he became friends with when they were juniors.

"What he went on to achieve was amazing, particularly here," Murray told a small group of reporters.