Roger Federer and Rafael Nadal came together for an incredible training moment as they tried to inspire Fabio Fognini, their European team mate, at the Laver Cup.
Fognini was playing the second game of the day against American Jack Sock.
But the Italian, who beat the Monte Carlo Masters in April, struggled to enter the opening set, losing 6-1.
The second set was a lot tighter, and when it was over, Federer and Nadal did their best to support Fognini.
In the 5-4 transition, with Sock serving alongside to stay on set, Federer and Nadal approached Fognini and asked him to be positive.
Federer said, “New balls now, okay, it's going to be pretty hard, number one.
“Number two, I don't want negative anymore. I just want positive. If you come back, do it because you have a good intention.
"If he hits a good forehand, okay, we respect, maybe he was lucky, it doesn't matter. Believe me in the good thing.
“You can't get frustrated and think something bad is going to happen or he's lucky. Make him hit a great shot and we accept it and continue. "
While Federer spoke to Fognini in English, Nadal greatly encouraged the Spaniard before sending the man back into action.
Commentator Mary Carillo said: “How is this change? Two of the greatest players of all time trying to tell you to stay positive. "
Todd Woodbridge added: “What a time to have Roger in transition almost teaching you what you need to do.
"And Fabio knows he's right. And the Italian in Fabio means to let him go, not listen and prove that Roger is wrong.
"But he can't do that in this environment. And then you have Rafa backing up, there's Fabio.
Finally, Fognini was unable to follow Federer and Nadal's advice by losing 6-1 7-6 to Sock.
After 12 months of injury, Sock's victory was his first singles victory since November 2018.
"It was a long way back," said Sock.
"I'm sure everyone here is surprised that I won an individual match. I had a thumb surgery in February and was gone for almost six months. For some reason, the Laver Cup seems to bring the best tennis ever here."
"I've played great singles before, so I know it's in me, but it's an incredible feeling to release it today by playing for these guys, not just me."
The win also tied the competition 1-1 after Dominic Thiem beat Denis Shapovalov 6-4 5-7 13-11 in an exciting opening match.