Serena shows ruthless side to reach last four
Fast and furious Serena Williams dropped just one game as she blew away China's Wang Qiang 6-1 6-0.
Wang, seeded 18th, did not manage to hit a single winner as she was taken apart in her first grand slam quarter-final.
It was the American's 100th career victory at the US Open and at 44 minutes, the match was the quickest at this year's tournament.
"It's really unbelievable," said Williams (38). "When I first started here I was like 16. I never thought I'd get to 100 wins and still be here but I love what I do.
"When I'm playing someone I know who's playing well, I have to step up or go home, and I want to stay here."
Williams showed no ill-effects from rolling her ankle during her fourth-round win over Petra Martic.
"I'm feeling good," she added. "It's been a tough year but physically I'm feeling great and more than anything I'm just having fun when I come out here."
Williams will play Elina Svitolina in the semi-finals.
"She's had a great year," said Williams. "She made the semis at Wimbledon and I feel she wants to go one step further, so I feel I'll have to come out and play really well."
Svitolina, the fifth seed from Ukraine, beat Britain's Johanna Konta 6-4 6-4 over 100 attritional minutes.
Belinda Bencic defeated Donna Vekic to reach her first grand slam semi-final.
The 22-year-old from Switzerland, who knocked out defending champion and top seed Naomi Osaka in the fourth round, won 7-6 (5) 6-3 against her close friend and frequent hitting partner.