Australian tennis up-and-comer Nick Kyrgios has received a stern warning from the ATP World Tour, after it handed him a six-month suspended $US25,000 fine and 28-day suspension for his recent controversies.

The youngster featured in a Nike promotional tour with the likes of Pete Sampras, Andre Agassi, Roger Federer and Serena Williams in New York ahead of the US Open, which is set to begin on Monday.

Sampras warned the world number 37 to “behave, young man” as the tournament got under way – a sentiment which was rehashed on Twitter by Canadian Genie Bouchard, who was also present.

Kyrgios must refrain from any ‘verbal or physical abuse’ indiscretions to avoid the hefty fine and suspension.