The occasion was the official opening of the newly renovated Margaret Court Arena that will give the Australian Open, which starts on Monday, its third stadium with a retractable roof.
On Wednesday, 7,500 fans crammed into the arena for a benefit night for the Rafa Nadal Foundation, which assists socially disadvantaged youth.
It also showcased the Australian-developed Fast4, which features major rule variations to speed up the action for players and fans -- no advantage scoring, lets are played, and the first to win four games wins the set.
The often no-nonsense Nadal, introduced to the crowd through a haze of dry-ice smoke and loud music, clearly enjoyed the new format.
He joked with the spectators on numerous occasions and once playfully hit a ball into the crowd when someone interrupted him during a serve.
He later took a few "selfies" with his mobile phone. Earlier Wednesday, Nadal had a training session at Melbourne Park, indicating he might be overcoming some recent health and injury issues.
Nadal was sidelined for three months with a right wrist injury after Wimbledon. He briefly returned in Beijing in late September, advancing to the quarterfinals.