Hopman Cup organisers have shelved the 2016 experiment with two Australian teams that was largely designed to accommodate Lleyton Hewitt on his retirement tour while still showcasing Kyrgios, the crowd-pleasing new generation star. The world No.15 will again partner Gavrilova, who also used the mixed teams invitational as the launch for a successful summer, highlighted by an appearance in the Australian Open's fourth round.

Yet the fact that Australia and Switzerland are in different groups means that Kyrgios, who was due to play sometime-mentor Radek Stepanek in the second round of the Japan Open, can only meet Federer if both teams reach the final. The 17-time major winner has not played since re-injuring his knee in the Wimbledon semi-final loss to Milos Raonic, and this will be his first visit to Perth since successfully partnering Martina Hingis 15 years ago.

"The men's field is very strong, coming up," Kyrgios said. "I think there is a little bit of pressure there. You know a lot of people want to win that event, it's a lot of fun and there has been some great champions there.

"Australia hadn't won it for a long, long time (since 1999, through Mark Philippoussis and Jelena Dokic) so to be coming back there it's pretty exciting to be defending the title."

The field, which includes four current top 20 and nine top 40 players, will be completed by Britain (Dan Evans, Heather Watson), France (Richard Gasquet, Kristina Mladenovic), and Spain (Feliciano Lopez, Lara Arruabarrena).

Already announced for the January 1-7 event were Switzerland (Federer, Belinda Bencic), the US (Jack Sock, CoCo Vandeweghe), Czech Republic (Adam Pavlasek, Petra Kvitova) and Germany (Alexander Zverev, Andrea Petkovic).