Smooth progress for Serena Williams as Kei Nishikori among big name casualties on first day of US Open

Serena Williams eased into the second round of the US Open ©Getty Images

Last year's runner-up Kei Nishikori of Japan was among big names to fall on the opening day of the US Open as Serena Williams got her calendar Grand Slam bid off to a typically comfortable start.

Nishikori, the Japanese player who lost to Croatia's Marin Cilic in last year's final, was beaten in a five-set thriller by Frenchman Benoit Paire.

After losing the first-set 6-4, Nishikori fought back to win the next two 6-3, 6-4.

A fourth-set tie break proved crucial, however, and after world number 41 Paire won it 8-6, he made the decisive break in the decider to win 6-4.

"It's always very sad to lose in the first round," said Nishikori, troubled with a hip injury leading into the tournament.

"But I think he was playing good tennis so I don't think I played bad."

Plenty more upsets followed on the women's side of the draw, with six seeded players exiting at the first hurdle.

Serbian seventh seed Ana Ivanovic was beaten 6-3, 3-6, 6-3 by 2014 Australian Open finalist Dominika Cibulkova of Slovakia, while eighth seed Karolina Pliskova of Czech Republic was thrashed 6-2, 6-1 by Georgia's Anna Tatishvili.

Tenth seed Carla Suarez Navarro also crashed out, along with Russia's 2004 winner Svelana Kuznesova and Serbia's former finalist Jelena Jankovic.

Kei Nishikori (right) was a big name casualty at the US Open after losing to Benoit Paire ©Getty Images

This followed the withdrawal of another Russian, world number three Maria Sharapova, who pulled-out on the eve of the tournament because of injury.

There was success for top seeded Williams, who took just 30 minutes to begin her bid to add the US Open title to her Australian Open, French Open and Wimbledon victories after Russian opponent Vitalia Diatchenko retired at 2-0 down in the second set having lost the opening set 6-0.

Her sister Venus, the two-time champion, joined her in round two, beating Puerto Rico's Monica Puig 6-4, 6-7, 6-3 for only her second victory since losing at Wimbledon two months ago.

Men's world number one Novak Djokovic demolished Brazil's Joao Souza 6-1, 6-1, 6-1, while eighth-seed Rafael Nadal gained a boost after a torrid year with a 6-3, 6-2, 4-6, 6-4 triumph over 18-year-old Croat Borna Coric 6-3, 6-2, 4-6, 6-4.

First round singles action is due to continue at Flushing Meadows tomorrow.