PERTH, Australia -- The mixed doubles team of Maria Sakkari and Stefanos Tsitsipas narrowly beat Croatia’s Petra Martic and Borna Gojo 7-6(6), 6-4 in a decisive fifth rubber in the Perth City Final.

Greece will now head to Friday’s United Cup semifinals against Italy.

This was the second City Final on Wednesday that came down to a mixed doubles result. Earlier, Iga Swiatek and Hubert Hurkacz led Poland to the final four.

In the day session, Croatia’s Donna Vekic kicked off the tie with a 6-2, 6-0 win against Despina Papamichail in 64 minutes. Stefanos Tsitsipas then helped Greece draw level, coming from 4-1 down in the third set to beat Borna Coric 6-0, 6-7(4), 7-5.

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Papamichail saved four break points in the opening game for an early hold. But Vekic converted her sixth break point of the day in the third game, winning an exchange that featured net cords and a cat-and-mouse volley exchange before Papamichail put a smash wide.

Thereafter, Vekic settled and began to dominate. The second set was near-flawless from Vekic, who conceded only eight points and did not face a game point during it.

The pressure turned to Tsitsipas, who responded by coming through in a topsy-turvy encounter with Coric.

The ATP No.4 had to dig deep as Coric staged a recovery after saving two match points serving at 5-6 in the second set. The Greek was then in trouble 4-1 down in the decider, but he rallied in the 2-hour, 32-minute win.

"Whenever I play [Borna], it’s definitely not easy, but I keep reminding myself that it doesn’t get better than this and his level of tennis is going to improve my level of tennis," Tsitsipas said after the match.

"So yeah, I’ve lost some, now I’ve won some too. It’s important to get matches against opponents like this that raise the bar high. They require you to find ways to win, even when you’re not feeling your best."

Next, Sakkari delivered a fine serving performance to stop Martic 6-3, 6-3 and give Greece a 2-1 lead in the tie. The WTA No.6 landed 67% of her first deliveries and won 73% of those points and was broken just once. She faced break points in only two games. By contrast, Martic's serve was not the weapon it can be, with only 54% of her first serves landed.

Gojo hit back on Croatia's behalf with an authoritative win over No.803-ranked Sakellaridis. The No.144-ranked Wake Forest alumnus' heroics had sealed their defeat of France one day earlier, and Gojo completed an unbeaten Perth singles campaign.

Gojo's win leveled the tie at 2-2, setting up the decisive mixed doubles match, which went to the Greek pair after 1 hour and 34 minutes of play.

The final four teams in the inaugural United Cup are Greece, Italy, Poland and the United States.