Matteo Berrettini, of Italy, serves to Taylor Fritz at the BNP Paribas Open tennis tournament on Oct 12, 2021, in Indian Wells, California. (MARK J. TERRILL / AP)

Matteo Berrettini has become the sixth player to qualify for the season-ending ATP Finals in Turin next month after the Italian reached the second round of the Vienna Open on Monday, the ATP said.

The 25-year-old, who will make his second appearance at the ATP Finals, defeated Australia's Alexei Popyrin 7-6(3) 6-3 in the opening round.

My words aren't going to describe the happiness I feel in my heart ... 2020 was a tough year for me on and off the court. Here I am about to play my second (ATP) Finals and I can't believe it.

Matteo Berrettini, Italian tennis player

The ATP Finals is played between the top eight men's singles players and doubles teams and will be held from Nov. 14-21.

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"My words aren't going to describe the happiness I feel in my heart," said the world number seven. "2020 was a tough year for me on and off the court. Here I am about to play my second (ATP) Finals and I can't believe it.

"I always have to remember where I started. I didn't dream about this, because it was so big, but now it's happening. I want to do my best."

Berrettini joins world number one Novak Djokovic, US Open champion Daniil Medvedev, Stefanos Tsitsipas, Alexander Zverev and Andrey Rublev in sealing spots for the ATP Finals, with Casper Ruud and Hubert Hurkacz next in line to qualify.

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Rafa Nadal is eighth in the standings but the 20-time major winner has already ended his season due to injury.

Berrettini's compatriot Jannik Sinner is also in contention, with the 20-year-old 10th on the leaderboard after winning in Antwerp.