Novak Djokovic upstaged by nine-year-old singer

New York: Novak Djokovic marched into the US Open fourth round on Saturday before happily being upstaged by a precocious, nine-year-old pop singer.

Djokovic had defeated Sam Querrey 6-3, 6-2, 6-2 and then batted off a series of routine post-match questions from the media.

But he then invited Zia Uehling, the daughter of a family friend, onto the platform to perform her impromptu act.

"She`s a prodigy, a future star, and this is a very valuable experience for her," said Djokovic.

"In a few years time she will be a big star and she`ll be up on this stage."

Zia -- "I have written five songs....and I have about two books that I`m working on right now" -- then rattled off one of her own compositions to the watching media.

"I will sing an original song I wrote called African Sun. I wrote this song to give hope to the children in Africa. I never really play without my guitar, so I`ll give it a try."

Zia is the daughter of Peter Uehling, a former pro and close friend of Djokovic since the world number one`s teenage years.

The Serb stays at the Uehling house at Alpine, New Jersey, when he is at the US Open.

"Novak is a really nice guy. We all love him and we all want him to win. I try and watch his matches here but sometimes my mom says it`s too late," said Zia, who has music in the blood as her mother was a backing singer with US rocker Cyndi Lauper and British punk band Siouxsie and the Banshees.

The star-struck youngster even benefitted from Lauper`s professional advice.

"I asked her what the secret was and she said `practice, practice, practice`."

Was she hopeful of following Djokovic into tennis when she was older?

"I played tennis but I told my dad that I had this need to sing," she said.