Novak Djokovic received treatment for a wrist issue during his United Cup match against Jiri Lehecka on Tuesday but the world number one battled to a 6-1 6-7(3) 6-1 win that put Serbia on track to pip Czech Republic 2-1 and make the quarter-finals.
Djokovic drew Serbia level at 1-1 in the $10 million mixed team tournament and had been scheduled to compete in the mixed doubles decider with Olga Danilovic before being replaced by the 20-year-old Hamad Medjedovic.
The young Serbian duo overcame Petr Nouza and Miriam Kolodziejova 4-6 7-6(2) 10-8 to send Serbia into the last eight where they will play hosts Australia on Wednesday.
Djokovic, gearing up for a tilt at a record-extending 11th Australian Open title this month, appeared to be bothered by his right wrist in practice and occasionally grimaced in the opening set at the RAC Arena.
The Serb had his wrist worked on by a trainer after the first set and Lehecka sensed an opportunity, winning the second set in a tiebreak.
Djokovic took a medical timeout before the start of the third and came out firing, running up a 5-0 lead before sealing the match.
The 36-year-old said the wrist was sore.
Greece were stunned by Chile in their Group B opener, with Maria Sakkari and Stefanos Tsitsipas losing 6-7(5) 6-3 10-6 to Daniela Seguel and Tomas Barrios Vera in the mixed doubles decider at Sydney's Ken Rosewell Arena.
AFP add, Brisbane Nadal begins match in almost a year Rafael Nadal began his first singles match in almost a year at the Brisbane International Tuesday against Dominic Thiem, kickstarting what could be the Spaniard's farewell season.
The 37-year-old has not played singles since a second-round loss at the Australian Open last year, undergoing two rounds of hip surgery.
The long lay-off raised fears his career could be over, but Nadal said this week he was always determined to make it back for the 2024 season.
He conceded there was "a high percentage" that it would be his last season, but left the door open to play on should his body hold up.
The 22-time Grand Slam champion made a low-key return on Sunday in a first round doubles match alongside countryman Marc Lopez, which they lost to Australian pair Jordan Thompson and Max Purcell.
The two men have played 15 times, with Nadal winning nine and Thiem six.
Nadal won both his opening service games to love against former US Open champion Thiem.
The Australian Open runs from Jan. 14-28 at Melbourne Park.
