The Pole was corrected by her American opponent 6-2, 6-2, in just over an hour, ten days before the start of the Australian Open (January 16-30).
Jessica Pegula, ranked third in the world, put on the pressure from the start by taking the first seven points, before finishing the first set in 39 minutes and breaking early in the second set to easily claim the victory.
It's a big disappointment for Iga Swiatek, who had beaten the American four times in 2022 and was the favorite after a remarkable last season.
"I played against her a lot, in lots of different conditions, but I felt she was clearly the fastest," reacted Jessica Pegula after the match.
"I think I did a really good job playing aggressively, serving smart and returning well," added the world No.3.
Pegula thus gave the first point to the United States (1-0), in this mixed team tournament, before Frances Tiafoe, 19th at the ATP, allowed the Americans to take off thanks, again, to a victory easy (6-3, 6-3) against Kacper Zuk (N. 245).
American Jessica Pegula celebrates her victory in the United Cup against Poland's Iga Swiatek on January 6, 2023 in Sydney, Australia © Saeed KHAN / AFP
"I think I'm playing one of the best tennis of my life, I'm having fun on the court," said Tiafoe.
The Americans only need one victory to reach the final.
On Saturday, Taylor Fritz and Madison Keys will face Hubert Hurkacz and Magda Linette respectively, before a possible double to decide between the two nations in the event of a tie at 2-2.
In the other semi-final, Greece faces Italy.
© 2023 AFP