Novak Djokovic has been announced as part of a lineup also featuring Jannik Sinner and Barbora Krejcikova for The HEAD NYC Mash Up, a pickleball exhibition event ahead of the 2024 US Open. Djokovic's inclusion has sparked outrage among tennis fans, who have recalled the Serb expressing concern earlier this year over how pickleball poses a threat to tennis.The former World No. 1 attended a press conference following his third-round win over Alexei Popyrin at the 2024 Wimbledon Championships. During the presser, Djokovic spoke about the rising popularity of padel and pickleball due to their affordability compared to that of tennis, which is much more expensive to pursue.The 24-time Major winner opined that in the long run, tennis' high expenses may prevent people from playing it and instead encourage them to take up padel and/or pickleball.On Monday, August 19, it was officially confirmed that Novak Djokovic, reigning Australian Open men's singles champion Jannik Sinner and reigning Wimbledon women's singles champion Barbora Krejcikova will feature in The HEAD NYC Mash Up on Thursday, August 22.Several tennis fans criticized Djokovic over his participation at the exhibition event, remembering the concerns he raised during his Wimbledon Championships campaign. One in particular left a stinging remark, suggesting that the Serb agreed to taking part in the event solely because of money."Yikes !!!!! after @DjokerNole complained the padel & pickleball is taking over tennis !!! Shocking ! Everyone has a price I guess….from Rafa representing the Saudis to Nole playing this crap now," they said.The fan also drew a parallel to Rafael Nadal being named as the ambassador of the Saudi Tennis Federation in January this year despite question marks over Saudi Arabia's human rights record and the similarly controversial state of women's rights in the country."Didn't Novak say that pickleball is endangering tennis???" another said."The bag must have been heavy but this is so hypocritical from Novak after his long rant at Wimbledon…??" a third fan said."Stepping into the dark side...... not you Djokovic," yet another said.There were others who took swipes at Novak Djokovic, Jannik Sinner and Barbora Krejcikova, while some expressed their desire to see the event shelved."Total sellouts," a fan said."Disgrace," another said."Stop this immediately," one said.Several tennis superstars have played their part in promoting and popularizing pickleball before Djokovic steps out to do the same on Thursday, August 22 at the exhibition event in New York.Novak Djokovic set to become the latest high-profile name in tennis to play pickleballNovak Djokovic (L) and Andre Agassi (Source: Getty)Before Novak Djokovic, Andre Agassi and Steffi Graf, arguably tennis' most iconic power couple, teamed up to play mixed doubles pickleball earlier this year at The Pickleball Slam 2. On the other side of the net was the duo of John McEnroe and Maria Sharapova.It was the Agassi-Graf combo that emerged triumphant. 2003 US Open winner Andy Roddick and 1989 French Open champion Michael Chang were a part of the first edition of The Pickleball Slam.There are some, such as former ATP World No. 2 Jack Sock and 2014 Wimbledon women's singles finalist Eugenie Bouchard, who have experienced pro pickleball. While Sock has become a full-time pickleball player after calling time on his tennis career, Bouchard is still an active tennis player, last featuring in the qualifying rounds of the National Bank Open in Toronto.