Serena Williams, Victoria Azarenka and Tsvetana Pironkova made up the mothers on tour who marched into the third round of the US Open on ...

Serena Williams, Victoria Azarenka and Tsvetana Pironkova made up the mothers on tour who marched into the third round of the US Open on Thursday, accounting for two of the three top-10 upsets.
Unranked Bulgarian Pironkova – playing her first tournament in three years after a break to have her first child – prolonged her participation with a 7-5, 6-3 upset of Spanish 10th Garbine Muguruza.
Former world number one Williams also advanced later Thursday with a 6-2, 6-4 win over Russia’s Margarita Gasparyan.
Williams and Pironkova were later joined by Azarenka, another former world number one who beat Belarussian compatriot and fifth seed Aryna Sabalenka 6-1, 6-3.
The 38-year-old Williams closed out the first set with ease before a slight wobble in the second when she was broken twice by Gasparyan. Williams’ straight sets win in 1hr 33min on the Arthur Ashe Stadium court put her into a third-round meeting with former champion Sloane Stephens, who overcame Belarusian Olga Govortsova 6-2, 6-2.
Williams, 38, looked in imperious form in the opening set, serving well and unfurling some thunderous groundstrokes to keep Gasparyan on the back foot. However she didn’t have it all her own way in the second, being broken twice by Gasparyan who clawed her way back to...