New York: 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.