Novak Djokovic has battled his way through a wrist injury as Serbia secured a dream United Cup quarter-final showdown against Australia on a day of high drama and confusion in Perth.

The world No.1 was troubled by his right wrist during practice on Tuesday morning, with the injury requiring intense treatment from his physio.

Djokovic was cleared to play his singles match against Jiri Lehecka later in the day and it was just as well given Wimbledon champion Marketa Vondrousova defeated Olga Danilovic 6-1 3-6 6-3 to give the Czech Republic a 1-0 lead in the tie.

The 24-time grand slam winner looked on track for an easy victory against Lehecka after winning the first set and shooting out to a 3-1 lead in the second.

But with his wrist troubles growing as the match wore on, Djokovic started making a series of uncharacteristic unforced errors.

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He took a medical timeout after losing the second-set tiebreak and came out firing with a double break in the third set to seal the 6-1 6-7 (7-3) 6-1 victory.

Djokovic is confident the wrist injury won’t hold him back for his highly anticipated match-up against world No.12 Alex de Minaur in Perth on Wednesday night.

“I think it’s not a major concern because I still managed to finish the match. I managed to play well,” Djokovic said.

“Even though I maybe wasn’t feeling 100 per cent, it still allowed me to finish the match.

“So hopefully I’ll have enough time to recover for tomorrow’s tie against Australia that is in the afternoon hours, so more time for us.”

Confusion reigned after Djokovic’s singles win on Tuesday as to whether Serbia had already done enough to qualify for the quarter-finals.

The initial declaration from officials was even if Serbia went on to lose the mixed doubles and therefore the tie, it would qualify for the quarter-finals as the best second-placed team in Perth.

But that proved to be wrong with organisers later clarifying Serbia would be out if it lost the mixed doubles in straight sets.

Djokovic opted out of the mixed doubles to rest his wrist and he faced a nervous wait to see if his teammates could pull through.

Things looked bleak for Serbia after Danilovic and Hamad Medjedovic lost the first set to Miriam Kolodziejova and Petr Nouza.

But Serbia’s passage was safe when it won the second set in a tiebreak, with Djokovic clearly delighted and relieved as he watched on from the sidelines.

Serbia went on to win the clash 4-6 7-6 (7-2) 10-8 in a match tiebreak.

-AAP