World number three Dominic Thiem will complete the field in the Ultimate Tennis Showdown (UTS), a 10-man league played over five weekends at an academy in Nice run by the coach of Serena Williams.
The competition drawn up by Patrick Mouratoglou begins this weekend but three-time Grand Slam finalist Thiem will miss the start, having already committed to a tournament hosted by Novak Djokovic in Belgrade.
Organisers said Thiem would play his first UTS match on June 20, with Frenchman Elliot Benchetrit, ranked 208th, stepping in for the Austrian for the first two rounds.
Canada's Felix Auger-Aliassime has been ruled out after injuring his right ankle Tuesday in training. He will be replaced by veteran Spaniard Feliciano Lopez.
US Open semi-finalist Matteo Berrettini will take on David Goffin in Saturday's opening round of matches, with sixth-ranked Stefanos Tsitsipas opposing Richard Gasquet.
Australian youngster Alexei Popyrin, Benoit Paire, Dustin Brown and Lucas Pouille are also taking part.
The six best-placed players after a round-robin format will advance to a knockout, with the top two qualifying directly for the semi-finals. All matches will be held behind closed doors because of the coronavirus pandemic.
Mouratoglou is aiming to attract a younger audience with an innovative competition that will allow viewers to hear conversations between players and coaches while encouraging a more relaxed on-court atmosphere.
The amount of prize money on offer has yet to be revealed.
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