Perth: 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 quarterfinals.
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.
"But I managed to play it through and it's not the first or the last time," he added. "These things happen. You just have to manage and find a solution. Let's see what happens now."
Wimbledon champion Marketa Vondrousova had earlier given the Czechs a 1-0 lead by beating Danilovic 6-1 3-6 6-3.
Poland will take on China in Wednesday's other quarter-final in Perth.
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.
Sakkari beat Seguel 6-0 6-1 in the opener before Chile's Jarry downed Stefanos Sakellaridis 6-3 3-6 7-5 to level the tie after the Greeks decided not to field Australian Open runner-up Tsitsipas in the singles.
The Australian Open runs from Jan. 14-28 at Melbourne Park.
—Reuters