The 22-year-old Nick Kyrgios, who upset Rafael Nadal in the quarterfinals at Cincinnati, will rise up when he gets to face the great players, but is less motivated at other times.

Kyrgios has beaten 15-time Grand Slam champion Nadal, 19-time major champ Roger Federer and the 12-time Grand Slam winner Novak Djokovic, going 5-3 against them combined.

The No. 23 admitted that he tries as hard as he can against the top names, but also says the other up-and-comers do the same—it's just that with him, the difference is more apparent.

“I think all the young guys play great against those guys. Look at [Alexander] Zverev. He’s killing it at the moment,” Kyrgios said. “Obviously it’s easier to say that for me, because you see me tank ridiculous amounts of matches against, like, on back courts and stuff, and you never see me doing anything silly in a match like this [against Nadal]. It’s easy to get up for these matches.

"Little kid playing on center courts of Cincinnati against Nadal, the best has to come out," he added.

What Kyrgios, who has won three singles titles, says he has to work on is playing that level of tennis consistently.

"The problem for me is trying to bring it on an everyday basis, say, center court of Lyon with 15 people against Nicolas Kicker earlier this year, I lost. Tonight I’m playing Rafa and I won," he said.

"These matches aren’t the problem. It’s those matches for me.”