The American team of Richey Reneberg and Lindsay Davenport had been seeded to face the Czech Republic in the last four, but were struggling from the moment Davenport lost 6-0, 6-4 to Medvedeva in the opening singles rubber.
Reneberg and Medvedev produced a high-class men's singles encounter which included two tie-breaks, before the world No 15 finally ensured Ukraine's moment of glory with a 6-7, 7-6, 6-3 victory.
It was the first time any team from the former Soviet Union had reached the semi-finals of the mixed team tournament, where Medvedev was keen to do well after defaulting through injury last year.
"I don't know how people will react in Ukraine, but we are both very proud," Medvedev said. "I think I almost played my perfect match . . . in the end I was lucky because he had two break points in the final set."
The Czech Republic, the defending champions, beat Australia, the hosts, 2-1, which took them to the last four for the sixth time in seven years. However, Petr Korda, unbeaten in the torunament for the last two years, had to struggle before he completed a2-6, 6-3, 7-6 win over Pat Cash. Jana Novotna was not stretched too far to secure the Czechs' progress by beating Kristine Radford 6-3, 6-3 in 69 minutes.Reuse content