World number one Serena Williams moved one step closer to completing first calendar Grand Slam since 1988 after she beat Dutch qualifier Kiki Bertens 7-6 (7/5), 6-3 at the US Open.
The three-time defending champion aiming to win her seventh US Open title, was dominated by her v early in the match.
The 33-year-old made 34 unforced errors and 10 double faults as she struggled to victory and continued her march towards history.
“I just kept fighting for each point, not for a lot but just one at a time,” Williams said.
“I had been pretty relaxed. Today I was a little tight. I think it showed. Hopefully I can get back to where I was before.”
“It definitely doesn’t worry me, being down a lot,” Williams said. “I know I can make a comeback, make a run for it.”
Williams completed her second “Serena Slam” of four major wins in a row by winning the Wimbledon crown in July and the 33-year-old American can claim her Open Era-record seventh US Open title as well as extend her mark as the oldest woman Slam champion.
She is now seeking to complete the first calendar Grand Slam since Steffi Graf in 1988. If she succeeds, she would equal Graf’s Open Era record of 22 Slam singles titles, two shy of Australian Margaret Court’s all-time record.
Next up for Williams will be fellow American Bethanie Mattek-Sands, who beat compatriot CoCo Vandeweghe 6-2, 6-1.