Tennis pro Novak Djokovic is off the market.

The world's no. 1 ranked tennis player is going to marry his high-school sweetheart, Jelena Ristic. The couple first met in high school in Belgrade and have been together ever since.

"We're engaged!!! Getting used to introducing Jelena as my fiancé and future wife," Djokovic, 26, wrote Wednesday on Instagram and posted a photo of Ristic kissing him on the cheek. "Couldn't be happier."

More: Novak Djokovic & Jelena Ristic PHOTOS

According to reports, the Serbian champion proposed to his girlfriend of eight years over the weekend in Monte Carlo, where he currently lives.

The newly engaged pair, known as the "Will and Kate of Serbia," plan to get married next year.

"Thank you all for wonderful wishes! #lucky #blessed #happy," Jelena Ristic wrote on Twitter.

The 26-year-old Serbian star won the Australian Open and reached the final at Wimbledon and the U.S. Open in 2013.