Ana Ivanovic crashed out of the US Open first round on Monday, losing 6-3,

3-6, 6-3 to Slovakia's Dominika Cibulkova and giving Serena Williams a helping hand in her

Grand Slam history bid.

Serbian seventh seed Ivanovic, a quarter-finalist in 2012, was in Williams's half of the

draw, a section which had already lost Maria Sharapova through injury even before the

tournament started.

World number one Williams is bidding to become the first woman since Steffi Graf in 1988 to

complete a calendar Grand Slam.

Cibulkova, ranked 50th in the world after sitting out three months to undergo surgery on her

left foot, will face American qualifier Jessica Pegula for a place in the last 32.

"It feels real cosy," said the 26-year-old Cibulkova of the huge superstructure which towers

over the Arthur Ashe Stadium and has been built to hold a retractable roof which will be in

operation next year.

The pint-sized Cibulkova made the quarter-finals in New York in 2010 but had fallen in the

first round in the last two years.

Monday's win, her third in five meetings against former French Open champion Ivanovic, opened

play at the 2015 tournament.

But it was not the greatest of encounters, with the fractured affair featuring 11 breaks of

serve while Ivanovic required treatment on her left foot after slipping 4-1 down in the

decider.

"I knew I had to bring my best tennis today. I had to stay tough as I knew she would not give

me a single ball," said Cibulkova.

With Ivanovic and Sharapova no longer involved, Williams finds eighth-seeded Czech Karolina

Pliskova as the highest-ranked player in her half.