Nick Kyrgios’ return to the Australian Open is over after he and partner Thanasi Kokkinakis stopped playing while trailing in the second set of their first-round doubles match.

Nick Kyrgios' Australian Open farewell could be at risk after his doubles partner, Thanasi Kokkinakis, raised concerns about his fitness to compete in their opening match in Melbourne.

Nineteen-year-old Learner Tien, a qualifier from California, just pulled off one of the biggest shocks of the Australian Open, defeating Daniil Medvedev in a thrilling five-set match. The 4-hour, 49-minute marathon contest began Thursday night and concluded early Friday morning on Margaret Court Arena.

The 19-year-old who was a late qualifier to the Grand Slam secured the biggest win of his young career on Thursday