Kyrgios and Tsitsipas sign on for Laver Cup

Nick Kyrgios and Stefanos Tsitsipas are taking their blossoming rivalry to Geneva for the Laver Cup. Announced on Tuesday, Kyrgios will return to Team World while Tsitsipas will suit up for Team Europe.

Kyrgios and the Greek faced off in Washington a few weeks ago after teaming up in doubles. The 24-year-old Australian won the semifinal showdown in a third-set tiebreaker, and helped his friend out along the way with a shoe delivery.

The 21-year-old's shoelace trouble was so prominent that Kyrgios thought it would make a good last-minute birthday present this week.

"I actually didn't get him a present. I didn't know until I saw it on Twitter this morning, but I don't know," Kyrgios said in Cincinnati. "I might get him something small tomorrow, maybe a shoelace or something."

In his Laver Cup debut, Tsitsipas will join the likes of Roger Federer, Rafeal Nadal, Dominic Thiem, Alexander Zverev and Fabio Fognini.

At the Western & Southern Open this week, Tsitsipas and Kyrgios will play doubles together again, opening against top seeds Robert Farah and Juan Sebastian Cabal on Tuesday.