Novak Djokovic, the world number one men's singles tennis player, was appointed Goodwill Ambassador by Unicef on 26 August. Since 2011, Djokovic had served as Unicef's Serbia Ambassador.

"In recognition of his deep commitment to children, Unicef is excited to welcome Novak to our global Goodwill Ambassador family. And I'm sure together we will reach the most vulnerable children with early childhood development. And with Novak's winning ways, we will give every child, everywhere, not just a fair start, but the best start and pave the way for a better future for all," said Yoka Brandt, the deputy executive director at Unicef during a news conference in New York in which she gave the tennis star the organisation's pin.

Responding, Djokovic said: "As somebody that was very fortunate in life to pursue his dreams and to realise his dreams, I share the same philosophy and I share the same mission on making sure that every child, not just in Serbia but worldwide, has the opportunity to dream and has a good start in their life because education is the fundamental basis for everything that is expected of them in their later adult life."

During the news conference, it was also announced that the Novak Djokovic Foundation would partner with the World Bank to promote early childhood development. Djokovic offered his best advice for children.

"It's about dreaming first and really believing in your dreams. I think every child should be encouraged to dream and should be given an opportunity to dream. Unfortunately, in my country and in many disadvantaged rural areas around the world, children live in such circumstances and they are discouraged to dream and unfortunately also plagued by fear and some social barriers to pursue their dreams. But I think that would be the first and most important advice - to dream and to really be brave enough and to have the courage to really live in your imagination and to visualize yourself of becoming somebody or something that you really want to become."

The tennis star is in New York to compete in the US Open which begins on 31 August.