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Alcaraz had lost his first match at his two previous appearances at the season-ending championships, but put that behind him with a 7-6(5) 6-2 win over Australian Alex de Minaur, with matches against Musetti and American Taylor Fritz to come.

"I'm just really, really happy with the level that I played today. First match is never easy," Alcaraz said. "After the match, I realised that this one was my first win in the round-robin on the first day."

Musetti was a late replacement for Djokovic after the Serbian 38 year-old withdrew through injury hours after beating the Italian in Athens.

"Obviously someone like Novak being in the group is always tough," Alcaraz said. "The experience he has in this tournament, the level he has on indoor court, it's quite good. I lost to him in 2023, and I played great. He killed me."

Musetti needed to beat Djokovic to make the cut for the eight-player Turin field but the defeat in Athens appeared to have put him out of the running.

However, the Serbian's withdrawal paved the way for the Italian to make his ATP Finals debut in the Jimmy Connors Group alongside six-times Grand Slam winner Alcaraz.

The 23 year-old Italian fell to Djokovic after a near three-hour match, and unlike Alcaraz, has not had the opportunity to practice at the Inalpi Arena in Turin.

"To be honest, I prefer Lorenzo. I'm not going to lie," Alcaraz said with a smile.

"If he's there, he deserves it because of the level he has put on in the matches, the tournaments he has done this year, and the level he showed this year.

"Let's see how he's going to be, how he's going to adapt. He's coming from Athens, and he couldn't feel the court at all."

Musetti did not see anything odd about the timing of Djokovic's withdrawal, more with the Serbian's decision to compete so close to the ATP Finals, also revealing the moment he found out.

"I think Novak, he was completely in the rules of the ATP, of the tournament itself," Musetti said.

"I think the strange situation was that he was playing literally the week before the Masters. That could be a little bit strange for a player who is already qualified.

"When he told me at the net after the match that he was not coming, honestly we had a laugh about it. I was curious all week if he was coming or not."

Djokovic's family own the tournament that took place in Athens. It has previously been staged in his hometown of Belgrade.