Novak Djokovic taken by surprise as fans sing 'Happy birthday' during practice

Novak Djokovic, who turned 33 today, got a heartwarming birthday wish from fans in Marbella, as they sang 'happy birthday' for him from their apartments.

The Serb, who was practising even on the special day, was taken by surprise as the people living in the buildings surrounding the court came out to their balconies and started singing for him. Novak Djokovic was seen bowing to them, as they clapped and cheered after completing the song.

The World No. 1 shared the video on his Instagram story as well as Twitter feed, thanking the fans for their special surprise.

It has been an unusual birthday for the Serb; a few months ago, he would not have expected to celebrate it in the midst of a lockdown. But as he turned a year older, the rest of the world took special effort to remind him what a fantastic asset he is to sport - and also to humanity in general.

ATP, all four Grand Slams wish Novak Djokovic

Various tennis organisations have taken to social media to extend birthday wishes for Novak Djokovic

As expected, all tennis organisations went big on the Serb's birthday, wishing him in unique ways on their social media feeds. ATP shared a special compilation video that combines the best bits of his personality, the highlights of his career, as well as some strong words of praise from his rivals.

Here's what his biggest competitors said about him in the video:

Roger Federer: "He just keeps on winning. That's what he's been doing. Not just once in a while, but week in week out."

Andy Murray "Doesn't give you anything for free. You need to earn each and every game against him. And that's tough."

Rafael Nadal: He arrives with that confidence, almost winning everything. He's almost unbeatable these days.

The social media accounts of all four Majors also extended their wishes to Novak Djokovic, who is one of just five men in the Open Era to have completed a Career Grand Slam. The World No. 1 has a tally of eight Australian Open, one Roland Garros, five Wimbledon and three US Open titles so far.

He is also the defending champion at Wimbledon and the Australian Open, both of which he won in five tight sets - against Roger Federer and Dominic Thiem respectively. Wimbledon shared a video of his best shots from the 2019 edition, asking fans to pick their favourite of the lot. His terrific forehand pass against Federer in the final has the lead at the moment.

Roland Garros shared a couple of photos of the 2016 champion, including one with him holding the trophy that completed his Career Slam.

Meanwhile, the Australian Open also made plenty of noise on the Serb's birthday – and why wouldn't they? With eight titles to his name at the Rod Laver Arena, Novak Djokovic is the most successful player in the history of the tournament.

US Open, on the other hand, decided to post content that was very unique to Novak Djokovic. They shared videos of the Serb playing midnight tennis with kids, as well as clips showing his incredible flexibility.

Many other tennis tournaments and journalists wished the Serb on their social media handles, some of them in offbeat ways.