Iga Swiatek has beaten Paula Badosa in three sets as Poland defeated Spain to knock out the hosts in the opening round of the Billie Jean King Cup Finals.

The world No.2 sealed Poland's spot in the quarter-finals against the Czech Republic after the world No.12 Badosa was beaten 6-3 6-7 (7-9) 6-1 on the indoor hard-court in Malaga.

Badosa scrapped to get back in the match by winning the second-set tiebreaker, but the former world No.1 roared back with a dominant third set and a break advantage of 8-3.

The match was delayed late in the third set for what organisers called a "medical incident" that apparently took place among the spectators inside Malaga's Palacio de Deportes.

"She pushed me," Swiatek said afterwards. "There was a lot of pressure in the tiebreaker and it went her way, but I knew I could get back in it in the third set."

She underscored the importance of Magda Linette's opening win in the tie for Poland.

"We both did it, and also the whole Polish team," the five-time grand slam winner Swiatek said after making her BJK Finals debut.

Linette took three hours and 50 minutes to finally subdue Sara Sorribes Tormo 7-6 (10-8) 2-6 6-4.

The match had originally been scheduled for Wednesday but was pushed back two days due to heavy rain in southern Spain which caused some flooding in Malaga.

Later, Emma Raducanu made a triumphant return to action as Great Britain cruised through to the quarter-finals with a win over Germany.

The 22-year-old looked sharp on her comeback from her latest injury setback, defeating Germany's Jule Niemeier 6-4 6-4 at Malaga's Palacio de Deportes.

That gave Katie Boulter the chance to clinch victory and she wasted no time in wrapping up a 6-1 6-2 win against Laura Siegemund, sending Britain through to a meeting with defending champions Canada on Sunday.

Also through are the Slovaks who came from behind to upset the USA 2-1, to advance to a showdown with Australia.

with PA