Keys loses the first set 4-6! The American survives two set points but cannot escape a third, with Krunic piling a powerful serve straight down the middle of the court. A wonderful opening set for the Serbian. Elsewhere, Bertens is 2-1 up in third, while Millman and Kukushkin are level-pegging.

Krunic ekes out another game, she’s 4-3 up in the first, and her force is proving problematic for Keys, who has made an inconsistent start. Meanwhile, Bertens is back on song, 15-0 up in the third after taking the second. On the grandstand court, John Millman has just lost the second to Mikhail Kukushkin, so they could be in it for the long haul.

Kiki Bertens has seemingly turned things around against Vondrousova, with the former 5-2 up in the second after losing the first. The Czech will serve to prevent Bertens from levelling things up. As for Madison Keys, a power battle is unravelling against Krunic, with the American just fizzing over a 94mph forehand winner. Krunic, though, leads 3-2, with the pair locked at deuce.

Aleksandra Krunic, the Russian-born Serbian who is ranked 49 in the world, has got off to a flyer against Madison Keys. She’s 2-0 up in the first, with a little perfection on serve paving the way so far. It is extremely early days but she the favourite trails in front a home crowd, just as Bertens does in the Louis Armstrong stadium. In the men’s, Millman is behind in the second against the Kazakh.

Vondrousova fights back to win the first set 7-6, winning 7-4 in the tie-break, and that match-up against Bertens is nicely primed for an upset. And Millman cruised to 6-4, but Kukushkin has bounced back from losing the first to go 2-0 up in the second. On Arthur Ashe, Madison Keys, last year’s beaten finalist, trudges out on the court, with the No 14 seed looking very relaxed.

He may not be the Australian everyone’s talking about, but John Millman has taken the first set 6-4 against Mikhail Kukushkin. Meanwhile, Bertens is having to slog it out with Vondrousova, with the Dutch rallying to take the first to a tie-break.

Bertens seems to have got a little nervy, with Vondrousova pulling back to 5-5. And she’s actually in front, 15-0 up in the 11th game of this first set. Elsewhere, Madison Keys is going to be up shortly, against Aleksandra Krunic, on the Arthur Ashe court. That precedes Kyrgios v Federer. Meanwhile, a reminder of how Serena got the better of Venus inside 72 minutes yesterday:

Kiki Bertens, the No 13 seed, is having fun in the opening set, a break and 4-3 to the good. In the men’s competition, John Millman is at 3-3 against Mikhail Kukushkin, of Kazakhstan.