Six-time champion Novak Djokovic will head into next week’s Australian Open uncertain of how his elbow will react to competition after a six-month break.

The Serb, 30, has not played since retiring against Tomas Berdych in the quarter-finals of Wimbledon in July.

Djokovic has not undergone surgery, but the decision to play in Melbourne was left until the eve of the tournament.

“It hasn’t yet been 100% healed but right now it’s at the level where I can compete,” he said.

“Every day is getting better. I’m hoping that it can be 100% at the start of the tournament. Throughout the tournament, I don’t know how it’s going to behave.

“Even if it’s 100% healed, after six months of no competition, you never know how you’re going to react.”

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Djokovic has been working with new coach Radek Stepanek in the off-season, and Andre Agassi flew into Melbourne on Saturday to join his team.

One of the changes they have made is to the Djokovic service action, which has been altered to take pressure off the elbow.

“I feel like I spend less energy but I’m more efficient,” he said. “I’m really looking forward to trying out my new serve.”

The 12-time Grand Slam champion has dominated at Melbourne Park in recent years, winning six times since 2008, and he still hopes to add to his tally of major titles.

“The fire, passion, and love for the sport still burns inside. I have great support from my family and close ones and people around the world,” he said.

“I do feel young inside, you know.”

Djokovic will be seeded 14th in Melbourne and opens against American Donald Young on Tuesday, with Frenchman Gael Monfils and German fourth seed Alexander Zverev also in his section of the draw.

Another player returning from injury in Melbourne is ninth seed and former champion Stan Wawrinka, who has not played since Wimbledon because of a knee injury.

The 2014 winner only made the final decision to play after completing a practice set on Saturday.

“It’s been tough, really tough, to get back on the place to be able to play again,” said the 32-year-old Swiss.

“But I’m feeling better. I’m slowly getting there.”

Wawrinka plays Lithuania’s Ricardas Berankis in the first round on Tuesday.