The two must successful men in the sport's history, Roger Federer and Rafael Nadal, teamed up at the Laver Cup earlier this week.
In a similar vein to golf's Ryder Cup, Team Europe took on Team World in a fast-paced three-day competition in Prague.
Nadal and Federer were naturally on Team Europe and teamed up in a doubles match for the first time in their long history on the tour.
Fans loved seeing the legendary duo come together, as they talked tactics, high-fived, laughed, hugged and cheered for one another.
"We were a team, training together," said Federer, as per tennisworldusa.org. "In such situations on the practice court you are almost happy when they beat you because it means they are well-shaped. Usually you do not like to lose but here we trained like a team does. If Rafa or any other player wanted to train at a certain hour, I was okay with it.
"These are little things that on the Tour don't happen because you think about yourself, you want to choose your hours and want to win practice session matches. Spending a week like this in group with Rafa and others, almost all of them who are top ten players, was very special."
Between them, they've won 35 men's singles grand slams and an incredible re-emergence saw the tour veterans clean up all four in 2017.
Federer, 36, has 19 grand slams to his name whilst Nadal - still only 31 - has 16.
How Nadal's personality has changed
Speaking after the Laver Cup, Federer discussed how Nadal's personality has changed during their time on the tour together.
"At the beginning he was very shy and respectful with other top 10 players, and especially because I was No. 1.
"Then as the time went on his personality increased and he started playing his chances. It was interesting to see him growing up until that he became the Champion he is today.
"We had hard and painful battles on court, issues as well, but there was always an enormous respect between us. We shared many strong moments on court and off court in a very friendly way. As soon as we grew up, I realised how much Rafa was important in my career.
"He will forever be my ultimate opponent. He was the one who helped me to improve the most and to be a better player. And at the same time I say if he didn't exist, I would have not won so much (laughter). Rafa's presence was an extra motivation."