(CNN)Serena Williams marched into the semifinals of the US Open for the ninth consecutive time with an assured 6-4 6-3 win over eighth seed Karolina Pliskova Tuesday.
It is the first time the six-time champion has beaten a top-10 opponent since returning from maternity leave.
The victory ensured the American got some measure of revenge for her 2016 US Open semifinal loss against the Czech.
The 36-year-old Williams overcame a 4-2 deficit in the first set to see off Pliskova in one hour and 23 minutes and reach the last four at Flushing Meadows for the 12th time in her career.
Williams -- aiming to win a first grand slam since giving birth to her daughter last September to tie Margaret Court's all-time record of 24 major wins -- will next play Latvia's Anastasija Sevastova, who beat defending champion Sloane Stephens 6-2 6-3 earlier Tuesday.
"I was having a baby at this time last year so I really have nothing to prove," Williams told the Arthur Ashe crowd after the win.
"I really feel now that I am playing free."
'I felt so bad I wasn't winning'
Williams struggled at the start of an error-strewn first set -- in which she made 22 of her 30 unforced errors -- before going on an eight-game run to secure victory over the 2016 finalist.
After the match Williams said she had taken confidence from the backing of a partisan crowd, which included Billie Jean King, actor Michael Keaton and director Spike Lee.