Carlos Alcaraz became the youngest player in the Open era to reach the quarter finals of the men’s tournament at Flushing Meadows after the 18-year-old Spaniard beat Germany’s Peter Gojowczyk 5-7, 6-1, 5-7, 6-2, 6-0 on Sunday.

Alcaraz, who is 18 years and four months old, is eight days younger than Andre Agassi when the American reached the 1988 US Open quarter finals and semi-finals, according to US Open statistics.

The Spaniard is also the youngest to reach this stage in New York since Brazilian Thomaz Koch in 1963, five years before the sport turned professional, when the tournament was known as the US Championships.

“It’s really tough to play these kind of matches, to play fifth sets,” Alcaraz told reporters. “I hope to play more second weeks, to play more quarter finals of Grand Slams. I didn’t expect to play (in the) quarter-finals here.”

Gojowczyk, 14 years older than Alcaraz and playing in the fourth round of a major for the first time, made a bright start to edge the first set, but was hampered by an injury to his thigh and took a medical timeout midway through the fourth.

The German fought hard but faded badly as the match wore on. Alcaraz closed out the match with a bagel in the decider, sealing victory in three hours, 31 minutes when Gojowczyk sent a forehand sailing long.

Alcaraz smashed 35 winners and seven aces while winning 15 points at the net, feeding off the energy of the vocal crowd on Grandstand, while his opponent ended the match with a whopping 84 unforced errors.

“In the first sets I thought that I reached my limit physically and mentally. I think the crowd was really, really important for me in this situation,” Alcaraz added.

On Monday Olympic gold medallist Alexander Zverev, seeded fourth, extended his winning streak to 15 matches with a 6-4, 6-4, 7-6 (9-7) victory over Italian 13th seed Jannik Sinner.

Indian Rohan Bopanna and his Croatian partner Ivan Dodig lost to fourth seeds Rajeev Ram and Joe Salisbury7-6 (7-4), 4-6, 6-7 (3-7) in the men's doubles pre-quarters.

Bencic ousts Iga

Swiss Olympic champion Belinda Bencic survived a punishing first-set tie-break to defeat seventh seed Iga Swiatek of Poland 7-6 (14-12) 6-3 in the fourth round on Monday.

The pair battled through the 23-minute tie-break under hot and sunny conditions at the Louis Armstrong Stadium as Iga saw her 5-2 lead in the tie-breaker evaporate when Bencic won four straight points, with each player making unforced errors.

An exhausted Bencic raised her hands in triumph after two hours and seven minutes. “I feel like I’m tested every match,” she said. “Definitely today it was more challenging for me.”

Leylah on song

Leylah Fernandez who upset defending champion Naomi Osaka in the third round, took down 2016 winner Angelique Kerber 4-6, 7-6 (7-5), 6-2 on Sunday.

“I did have to pinch myself a little bit to see that it actually happened,” Fernandez, who turns 19 on Monday, said.

Second seed Aryna Sabalenka beat her former doubles partner Elise Mertens 6-4, 6-1 to move into the quarter finals here for the first time.

Barbora Krejcikova overcame breathing difficulties to beat Garbine Muguruza 6-3, 7-6 (7-4). Krejcikova, who called a medical time out late in the second set, looked in distress after the match. “At the end I was really struggling and I feel really bad right now," said Krejcikova, who skipped her post-match news conference.

For Muguruza, it was a familiar end to her Flushing Meadows campaign. She has won the French Open and Wimbledon, reached the final in Australia but has failed to reach the quarter finals at the US Open.