Italian men will be in record numbers in the French Open third round behind flag bearer Matteo Berrettini, who battled to a 6-4 4-6 6-2 6-3 victory over South African Lloyd Harris on Thursday.

The seventh seed joined NextGen APT Finals winner Jannik Sinner, Lorenzo Sonego, Stefano Travaglia and 2018 semi-finalist Marco Cecchinato as one of five Azzurri in round three - a record since tennis turned professional in 1968.

Sinner, Sonego, Travaglia and Cecchinato advanced on Wednesday, putting pressure on the highest-ranked Berrettini.

"I'm really happy. For myself and for the others," Berrettini told a news conference.

"Let's hope we can continue like this but I feel it's just the beginning as we are young."

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The 24-year-old world number eight overcame a dip in concentration in the second set to book a meeting with German qualifier Daniel Altmaier.

"Since the beginning I felt it would be a tough match. In the first set I was down a break, then in the second set I had a lot of chances but he broke me," Berrettini said.

"I think I was playing well in the third and fourth sets, I was hitting better, moving him better around the court."

Berrettini shook off early nerves to turn the tide after going a break of serve down, winning four games in a row and bagging the opening set when Harris sent a backhand wide of an open court.

Berrettini fell a break behind again in the second but this time he was unable to overturn the situation, making too many unforced errors as he grew frustrated on a floodlit court Suzanne Lenglen.

"I was really angry because I had chances but when you have chances and then you find yourself trailing, it's tough to stay in the match," he said. "But then I changed my mindset."

The third set was more straightforward as world number 90 Harris ran out of steam.

His double fault in the sixth game of the fourth set gave Berrettini another service break and the Italian went on to clinch victory on his second match point