Stefanos Tsitsipas inspired Greece to a comeback win at the United Cup, winning his singles and doubles matches to earn a 2-1 win over Spain on Saturday. 

Tsitsipas, along with partner Maria Sakkari, came from a set down to beat Yvonne Cavalle-Reimers and Sergio Martos Gornes 4-6 6-3 8-6 in the Group C clash. 

Sakkari made amends for her shock singles loss earlier in the day, when she was beaten 6-2 6-1 by Jessica Bouzas Maneiro to hand Spain the advantage.

Tsitsipas had levelled up the contest by overcoming Pablo Carreno Busta 6-4 3-6 6-3, recovering from a break down in the deciding set to keep the tie alive. 

In a nervy winner-takes-all mixed doubles rubber, Tsitsipas and Sakkari held their nerve to boost their hopes of finishing top of the group. 

Sakkari stood firm, holding two serves at 7-6 against the oncoming Martos Gornes, then striking a winner past the Spaniard to bring up three match points, which they converted. 

"We came clutch when we had to; that tie-break was good from our side," Sakkari said. "It's always amazing to play alongside Stefanos and create good moments on the court."

"There isn’t a single Greek night without some drama," said Tsitsipas. "I’m grateful that I have a fighter like Maria beside me. She never disappoints, she delivered until the end."

Greece will look to finish at the summit of Group C when they face Kazakhstan on Monday, after Elena Rybakina inspired a first United Cup victory for her country over Spain. 

In Group F, Australia were stunned on home soil as they fell to a 2-1 defeat to Argentina at the Ken Rosewall Arena, denting their chances of a maiden United Cup victory. 

Nadia Podoroska, the 2020 Roland Garros semi-finalist, fought through her season opener in the first match of the tie to give Argentina a 1-0 lead, beating Olivia Gadecki 6-2 6-4. 

But Australia drew level when Alex de Minaur produced a nearly flawless display to force a deciding mixed doubles clash, beating Tomas Etcheverry 6-1 6-4 in just over an hour.

He is now 5-2 in singles at the United Cup. In 2023, he defeated Rafael Nadal before earning three wins against top-10 opponents the following year, including Novak Djokovic.

"I think just being back here in Sydney [helped]. I love it here," De Minaur said. "I love playing here.

"I get to play in front of friends, family and in front of my home crowd, so what better way to start the new season?"

But De Minaur's efforts mattered for little after he watched Ellen Perez and Matthew Ebden be beaten by Maria Lourdes Carle and Etcheverry 6-2 6-4 in the decider.