World number one and top seed, Poland’s Iga Świątek recovered from a shaky start to avoid an upset by coming from behind to defeat unseeded Jule Niemeier and reach the last eight of the US Open in New York.
The Pole trailed by a set and a break but fought back to win 2-6 6-4 6-1 against German Jule Niemeier.
The 21-year-old has been the standout WTA player this season and is aiming for an impressive seventh title in 2022.
Świątek became world number one following Ashleigh Barty's shock retirement in March, but has fully justified her position by going on a remarkable 37-match winning streak.
Her relentless form led to six titles in a row, winning in Doha, Indian Wells, Miami, Stuttgart and Rome before adding the second triumph of her career at Roland Garros.
Despite a slight drop-off recently she had not lost a set in New York until Niemeier went ahead.
Świątek made many errors in the first set and start of the second, enabling Wimbledon quarter-finalist Niemeier to threaten a major upset and continue her breakthrough season with a notable win.
But the German began making mistakes at crucial times - particularly with double faults - and Swiatek slowly improved to better last year's run to the fourth round at Flushing Meadows.
“I'm proud I just didn't lose hope,” said Świątek.
“She was playing really good in the first set and in the second set I tried to focus on the small things that are the base for us. I'm pleased I kept my level.”
The reigning French Open champion will play American Jessica Pegula, who beat Czech 21st seed Petra Kvitova in the quarter finals.