SYDNEY -- No. 1-ranked Iga Swiatek led Poland into the quarterfinals of the United Cup mixed teams tennis tournament on Monday, winning both her singles and doubles matches.

Swiatek took the court under pressure, needing to win her singles match against Spain's Sara Sorribes Tormo to keep the tie alive. Alejandro Davidovich Fokina had given Spain a 1-0 lead with a 3-6, 6-3, 6-4 comeback victory over No. 9-ranked Hubert Hurkacz.

But Swiatek beat Sorribes Tormo 6-2, 6-1 to force a deciding mixed doubles match. Swiatek, a four-time Grand Slam singles champion, and Hurkacz then needed little more than half an hour to wrap up the tie with a 6-0, 6-0 win to make Poland the first country through to the quarterfinals.

In Sydney, three-time Grand Slam singles finalist Casper Ruud kept Norway's quarterfinal chances alive with similar victories in the singles and mixed doubles against Croatia.

Donna Vekic gave Croatia an early 1-0 lead with a 7-5, 3-6, 6-3 win over unheralded Malene Helgo. But Ruud then beat Borna Coric 6-4, 6-1 to send the tie to a decisive mixed encounter, which Norway claimed in a match tiebreaker.

The 6-2, 3-6, 10-7 victory for Ruud and Ulrikke Eikeri over Vekic and Ivan Dodig leaves Norway (1-1) awaiting the outcome of the last remaining Group F match between Croatia (0-1) and the Netherlands (1-0) on Tuesday.

In later matches Monday, the United States played Britain in Perth and France played Germany in Sydney.

Two quarterfinals from the Perth group games will be played Wednesday. The Sydney quarterfinals will be played Thursday and Friday, with the semifinals and final set for Saturday and Sunday, also at Sydney's Ken Rosewall Arena.