Zverev gave a surprise answer, revealing that his brother Mischa had borrowed it and claiming he had not seen it since.
“That’s actually a good question because my brother took it for a media appearance once,” the world number three said.
“He didn’t give it back to me yet. I don’t know where it is [and I haven’t] for the past five months.
“So, hopefully he hasn’t sold it on eBay or something like that!”
In the absence of world number one Djokovic, Zverev is one of the front runners to win the title in Melbourne.
