Novak Djokovic has had a difficult year due to issues with his COVID-19 vaccination status © Getty Images

Tennis star Novak Djokovic met with Serbia's Paralympic team on the side-lines of the Serbian Open in Belgrade.

The men's world number one referred to them as "true heroes" for their success against all odds. 

Djokovic was pictured laughing with the Paralympic team and exchanged tennis balls and table tennis bats with them.

The Serbian met with his countrymen after an exhausting win over 26-year-old compatriot Laslo Đere in the round of 16.

Djokovic came back from a set down to beat Đere 2-6, 7-6 (6), 7-6 (4) in what was a gruelling contest lasting nearly three and a half hours.

The 20-time Grand Slam champion's season has been majorly disrupted by the ongoing controversy surrounding his COVID-19 vaccination status.

As a result, he has struggled to find high-level competition this year, although he is scheduled to play at Wimbledon from June 27 to July 10.