Shocks come in so many gradations in tennis these days that even the first-round exit of the defending champion, Angelique Kerber, at the precocious hands of the 19-year-old Japanese Naomi Osaka in 65 minutes on day two was less seismic than the departure of Johanna Konta on day one.

The fragile German has tumbled to No6 in the world and arrived in disarray after losing in the second round in Cincinnati. Her confidence looks shot to pieces and Osaka, a talent ranked No45, was relentless in recording the biggest win of her career, 6-3, 6-1, under the new roof on Arthur Ashe Stadium. Kerber’s second serve let her down badly and she could not get the ball moving from hand at more than 95mph. Osaka was pinging them down at 108mph and struck 22 clean winners.

US Open: 2016 champion Kerber out, plus Nadal in action on day two – live! Read more

Kerber, indeed, was not among the favourites nor even one of the eight players capable of finishing the tournament as world No1. She has had a desperately uneven time of it since last year.

By failing to reach the Wimbledon final this summer she had already surrendered her No1 ranking. Karolina Pliskova – who lost to Kerber in last year’s final but is now at the summit of the game – vies with Garbiñe Muguruza, the Wimbledon champion, as favourite here.

Pliskova also had the benefit of the roof as steady rain wiped out the rest of the card on uncovered courts. She beat the Pole Magda Linette, 72 in the world, 6-2, 6-1 in an hour and 19 minutes. The Czech said: “Before every first-round match I’m a little bit nervous but especially in a grand slam - and especially having to defend so many points from the final last year. My serve could be better but, overall, I think it was solid.”

On a wet, dull Tuesday only a handful of matches were completed. Rafael Nadal got his campaign off to a reasonable start, beating the 27-year-old Serb Dusan Lajovic 7-6 (6), 6-2, 6-2 in two and a quarter hours.

The Spaniard, aiming for his third title here, has dipped a little since winning his 10th French Open, blowing up at Wimbledon, going out in the third round in Montreal and inheriting Andy Murray’s No1 ranking by reaching the quarter-finals in Cincinnati, where he lost to Nick Kyrgios.

He is looking for his championship tennis but was comfortable enough against Lajovic, ranked 85 in the world. He came desperately close to losing the first set, coming back from 3-5 down and holding his opponent at bay when he was serving for the frame.

Among the scheduling casualties on Tuesday was Britain’s Aljaz Bedene, whose match on an outside court against the Russian Andrey Rublev was among the contests postponed until Wednesday.

They are second on, while his compatriots Kyle Edmund and Cameron Norrie play their second-round matches at the tail-end of the day’s programme.