Poland's Swiatek looked in big trouble against Switzerland's Olympic champion Belinda Bencic and saved two match points in the second set before clawing out a 6-7(4) 7-6(2) 6-3 victory.
As the evening gloom set in, Swiatek eventually got a handle on her opponent's game, moving clear in the final set before wrapping up victory after more than three hours.
Bencic will look back at the two match points she had at 5-6 in the second set, the first saved with a powerful Swiatek forehand and the second with a backhand winner.
"I don't know if I even came back from match point down in my career," Swiatek said in her on court interview.
"I thought it was a great tennis match.
Persons:
Iga Swiatek, Switzerland's Belinda Bencic, Dylan Martinez, Ukraine's Elina Svitolina, Poland's Swiatek, Belinda Bencic, Andrey Rublev, Alexander Bublik, Novak Djokovic, Hubert Hurkacz, Roger Federer's, Sinner, Colombia's Daniel Galan, Swiatek, Svitolina, Azarenka, Jessica Pegula, Pegula, Marie Bouzkova, Rublev, Russian Roman, Denis Shapovalov, Martyn Herman, Christian Radnedge
Organizations:
Lawn Tennis, Croquet Club, Switzerland's Belinda Bencic REUTERS, Dylan Martinez LONDON, Wimbledon, Switzerland's Olympic, Belarusian Victoria Azarenka, Roger Federer's Wimbledon, Thomson
Locations:
London, Britain, tennis, Belarus, Russia, Belarusian, American, French, Russian