PERTH, Australia (AFP) — Iga Swiatek left Spain reeling on Monday as Poland booked a 2-1 win to move into the quarter-finals of the United Cup whilst holder United States was beaten by host Australia.

The 2-1 victory for Australia propelled it into the last eight as well.

World No. 1 Swiatek showed no mercy to Sara Sorribes Tormo in a 6-2, 6-1 singles victory before teaming up with Hubert Hurkacz to clinch the tie with a 6-0, 6-0 mixed doubles thrashing in just 53 minutes.

Hurkacz was ambushed in the day's opening singles, losing 3-6, 6-3, 6-4 to Alejandro Davidovich Fokina.

The top-seeded Poles finished Group A play with a perfect 2-0 record and await a last-eight opponent.

Swiatek, who has lost only seven games in two singles matches to start her countdown to the Australian Open, said playing mixed doubles was good experience.

"It's lessons for the future and great practice," the 22-year-old said.

"I hardly ever play mixed. You use different skills, it's about feeling the geometry of the court."

Hurkacz credited his teammate with doing most of the hard yards.

"She carried me throughout the whole match, in every game she was making amazing shots," the world No. 9 said.