Poland will face the United States in Sunday's final of the mixed-team United Cup following a dramatic end to the semi-finals in Sydney.
Iga Swiatek beat Elena Rybakina in straight sets to seal her side's victory against Kazakhstan while the US won 2-0 against the Czech Republic.
Coco Gauff beat Karolina Muchova 6-1 6-4 in the women's singles before Czech player Tomas Machac retired when leading 7-6 (7-4) 5-6 against Taylor Fritz.
"He said he had been cramping for a couple of games - I didn't notice," said Fritz, who had broken back after facing two match points and was serving for the second set when Machac approached the net to concede.