Wales rugby star Gareth Thomas praised the Duke of Sussex for his efforts in raising awareness about HIV testing as they met at a rugby club to highlight the issue.
Thomas, who revealed in September that he is HIV positive, said Harry has "done so much to normalise HIV testing and fight the stigma across the globe".
Harry and Gareth met players from the King's Cross Steelers, who style themselves as the world's first gay rugby club, and others from Premiership Rugby club Harlequins, to raise awareness about the issue.
Watch the moment the pair met:
Gareth was the highest-profile sportsman in the UK to reveal he was gay when he came out in 2009. Earlier this year, he said he was forced to reveal his HIV diagnosis after a tabloid newspaper threatened to publish it.
The ex-fullback, who captained both Wales and the British Lions, is thought to be the first UK sportsman to go public about living with HIV.
In recent interviews he said he was driven to suicidal thoughts as a result of his diagnosis but Harry and his brother the Duke of Cambridge have praised the Welshman for revealing he was HIV positive.
The pair decided to work together after Harry texted Gareth asking to chat a few days after the former rugby player revealed his HIV status in September.
A video he posted to Twitter to make the announcement has been watched almost five million times.
Charity The Terrence Higgins Trust said the day after the Welshman's announcement was the charity's busiest since launching their HIV self-test kits.
Its chief executive Ian Green said Gareth was "proof that a HIV diagnosis shouldn't stop you from doing anything".
Since going public, Gareth, also known as 'Alfie' has been challenging assumptions about the illness.
He recently completed a 140-mile Ironman triathlon to “break the stigma” around the illness, completing the feat in just over 12 hours.