New York - French Open champion Garbine Muguruza and Wimbledon runner-up Milos Raonic crashed out of the US Open on Wednesday as the $150 million roof on Arthur Ashe Stadium rolled smoothly into action for the first time.
Third seeded Spaniard Muguruza, who has struggled in the aftermath of her Roland Garros breakthrough in June, slumped to a 7-5, 6-4 loss to Latvia's Anastasija Sevastova, the world number 48.
A horribly out of sorts Muguruza rallied from 1-5 down in the second set, saving three match points, but Sevastova, who briefly quit the sport in 2013, held her nerve for the victory.
Having not won a match at the US Open in five years before this week, 26-year-old Sevastova now goes on to face Kateryna Bondarenko, a 5-7, 7-6 (7/5), 7-5 winner in three hours over China's Zheng Saisai.
"This is why I came back to the sport for the big stages like this and night sessions at the Slams. But I was shaking a little at the end," she said.
Muguruza admitted she had been outplayed.
"It was a very tough match. I think I didn't play well. Everything she was doing was working," said the 22-year-old who has never made the third round in New York.
Meanwhile, 120th-ranked Ryan Harrison of the United States stunned fifth seeded Raonic 6-7 (4/7), 7-5, 7-5, 6-1 in another second round upset.
"It was extremely physical out there. I was playing on adrenaline," said 24-year-old qualifier Harrison who was as high as 43 in the world in 2012.
He goes on to face experienced Cypriot Marcos Baghdatis for a place in the last 16.
Harrison has now reached the third round of a Slam for the first time after recording just a second win over a top 10 opponent in 27 meetings.
Raonic, considered as a potential title dangerman in New York, hit 69 winners but committed 62 unforced errors.
"I started cramping midway through the second set. There was a lot of nerves and stress. It was a result of over-exuberance," said 25-year-old Raonic.
Rafael Nadal, the 2010 and 2013 champion, eased past Italy's Andreas Seppi 6-0, 7-5, 6-1 in a match which became the first to be completed under the new retractable roof on Ashe.
Light rain caused the structure to be closed at 3-3 in the second set with play only held up for around seven minutes.
"It's part of history and I am very happy to be the first to play under the roof," said Nadal, who was also the first to practice beneath the roof on the cavernous 22 000-capacity arena.
Nadal beat Seppi for the eighth time in nine matches and next faces Russia's Andrey Kuznetsov.
World number one Novak Djokovic made the last 32 of a major for the 33rd successive time without hitting a ball when Jiri Vesely of the Czech Republic withdrew from their second round encounter suffering an inflammation of the left forearm.
Djokovic will face 34-year-old Russian Mikhail Youzhny, twice a semi-finalist, on Friday for a place in the last 16.
Britain's Johanna Konta, the 13th seed, collapsed on court with heat sickness before completing a 6-2, 5-7, 6-2 win over Bulgaria's Tsvetana Pironkova.
After a medical timeout, the Briton dropped the second set before heading off on a lengthy toilet break which did little to help her opponent's composure in the decider.
"I'm a little embarrassed. I'm not a fan of drama. I did the best that I could with the cards that I had," said Konta.
Angelique Kerber, the second seeded Australian Open champion, made the last 32 by seeing off 34-year-old Mirjana Lucic-Baroni of Croatia 6-2, 7-6 (9/7).
Kerber faces 17-year-old CiCi Bellis of the United States, for a place in the last 16.
Croatian seventh seed Marin Cilic, the 2014 champion, made the last 32 by seeing off Sergiy Stakhovsky 6-1, 6-2, 6-3.
Results from the third day of the 2016 US Open tennis championships at Flushing Meadows on Wednesday (x denotes seeded player):
Novak Djokovic (SRB x1) bt Jiri Vesely (CZE) walkover
Mikhail Youzhny (RUS) bt Guido Pella (ARG) 6-2, 6-1, 7-6 (7/3)
John Isner (USA x20) bt Steve Darcis (BEL) 6-3, 6-4, 6-7 (10/12), 6-3
Kyle Edmund (GBR) bt Ernesto Escobedo (USA) 7-5, 6-4, 6-4
Jo-Wilfried Tsonga (FRA x9) bt James Duckworth (AUS) 6-4, 3-6, 6-3, 6-4
Kevin Anderson (RSA x23) bt Vasek Pospisil (CAN) 7-6 (7/3), 6-4, 6-4
Jack Sock (USA x26) bt Mischa Zverev (GER) 6-1, 6-1, 6-2
Marin Cilic (CRO x7) bt Sergiy Stakhovsky (UKR) 6-1, 6-2, 6-3
Rafael Nadal (ESP x4) bt Andreas Seppi (ITA) 6-0, 7-5, 6-1
Andrey Kuznetsov (RUS) bt Albert Ramos (ESP x31) 7-5, 6-4, 7-6 (7/5)
Lucas Pouille (FRA x24) bt Marco Chiudinelli (SUI) 4-6, 3-6, 7-6 (8/6), 6-2, 6-0
Roberto Bautista (ESP) bt Federico Del Bonis (ARG) 5-7, 6-2, 6-3, 6-2
Gael Monfils (FRA x10) bt Jan Stral (CZE) 7-5, 6-4, 6-3
Nicolas Almagro (ESP) bt Pablo Cuevas (URU x18) 7-6 (7/5), 6-4, 7-6 (11/9)
Marcos Baghdatis (CYP) bt Benoit Paire (FRA x32) 6-2, 6-4, 3-6, 6-4
Ryan Harrison (USA) bt Milos Raonic (CAN x5) 6-7 (4/7), 7-5, 7-5, 6-1
Madison Keys (USA x8) bt Kayla Day (USA) 6-1, 6-1
Naomi Osaka (JPN) bt Ying-Ying Duan (CHN) 6-4, 7-6 (7/3)
Monica Niculescu (ROM) bt Ana Bogdan (ROM) 6-0, 6-1
Caroline Wozniacki (DEN) bt Svetlana Kuznetsova (RUS x9) 6-4, 6-4
Johanna Konta (GBR x13) bt Tsvetana Pironkova (BUL) 6-2, 5-7, 6-2
Belinda Bencic (SUI x24) bt Andrea Petkovic (GER) 6-3, 6-2
Kateryna Bondarenko (UKR) bt Zheng Saisai (CHN) 5-7, 7-6 (7/5), 7-5
Anastasija Sevastova (LAT) bt Garbine Muguruza (ESP x3) 7-5, 6-4
Roberta Vinci (ITA x7) bt Christina McHale (USA) 6-1, 6-3
Carina Witthoeft (GER) bt Yulia Putintseva (KAZ) 6-1, 6-7 (1/7), 6-1
Lesia Tsurenko (UKR) bt Wang Yafan (CHN) 7-5, 6-3
Dominika Cibulkova (SVK) bt Evgeniya Rodina (RUS) 6-7 (5/7), 6-2, 6-2
Petra Kvitova (CZE x14) bt Cagla Buyukakcay (TUR) 7-6 (7/2), 6-3
Elina Svitolina (UKR x22) bt Lauren Davis (USA) 6-1, 4-6, 6-3
CiCi Bellis (USA) bt Shelby Rogers (USA) 2-6, 6-2, 6-2
Angelique Kerber (GER x2) bt Mirjana Lucic-Baroni (CRO) 6-2, 7-6 (9/7)