Sixth seed Petra Kvitova defeated Kateryna Kozlova 7-6, 6-2 to cruise into the third round of the US Open here on Wednesday. In another early match, Angelique Kerber fought off a tough test from fellow German Anna-Lena Friedsam to win 6-3, 7-6.

Earlier on Tuesday, with no fans to cheer her on, Serena Williams was left to push herself to a record-breaking straight-sets victory in the first round.

The six-time champion won 7-5, 6-4 win over the 96th ranked Kristie Ahn.

Serena improved her first round match record to 20-0 and collected her 102nd US Open match win to surpass the mark she shared with Chris Evert.

Milos Raonic, the world No.3, advanced to the second round with a clinical 6-3, 6-2, 6-3 win over Leonardo Mayer.

Three-time champion Kim Clijsters fell at the first hurdle in her second comeback here when Ekaterina Alexandrova rallied for a 3-6, 7-5, 6-1 victory.

Russian third seed Daniil Medvedev faced little resistance from Federico Delbonis of Argentina in a 6-1, 6-2, 6-4 win. Former world No. 1 Victoria Azarenka, who is living in a house with her three-year-old son and mother, breezed into the second round with a 6-1, 6-2 win over Austria’s Barbara Haas.

Karolina Muchova took advantage of an error-prone Venus Williams to advance 6-3, 7-5 into the second round.

Meanwhile, German doubles player Tim Puetz has said that the second hotel of the biosecure bubble in Long Island was hosting weddings and parties and there was no security to stop players going out if they wished. “The USTA... never communicated that we players in the second hotel were not in a bubble. The other hotel with the other 90 per cent of players is different. It is completely booked by the USTA and there is security at every entrance.”