It's official! Djokovic set to marry girlfriend Ristic

World No 1 tennis player Novak Djokovic, announced via social media on Wednesday that he was engaged to marry his longtime girlfriend, Jelena Ristic.

"Meet my fiance (sic) and future wife," Djokovic, 26, said in a tweet that linked to a photo of the Serbian-born tennis star being kissed by his fiancee, also a Serb. "So happy! Thank you for the wonderful wishes #NoleFam and friends!"

Ristic is well-known to tennis fans as a fashionable and enthusiastic presence at Djokovic's matches and is director of his charitable foundation.

Getting used to introducing Jelena as my fiancé and future wife :) So happy! Djokovic wrote on his Facebook page.

Djokovic became a top-10 player on the ATP tour in 2007 but was overshadowed for several years by Roger Federer, the so-called Swiss Maestro, considered by many to be the greatest tennis player of all time, and Spaniard Rafael Nadal.

But in 2011 Djokovic surged past both men to claim the number 1 ranking.

Djokovic, who credits his rise to the top of his sport in part thanks to a gluten-free diet, in August released an autobiographical book about his nutrition and training regime, titled "Serve to Win."