PERTH, Australia -- Greece have sealed the first victory of Group A at the United Cup in Perth after Maria Sakkari defeated Viktoriya Tomova 6-3, 6-2 in 1 hour and 27 minutes, giving her team an unassailable 3-0 lead over Bulgaria.

WTA No.6 Sakkari had lost to Tomova in their first meeting, over six years ago in the 2016 Szeged ITF W50 final. But she had gained revenge in the second round of Wimbledon 2022, and once again showed how far she has come in establishing herself as a solid Top 10 player.

The first half of the opening set was tightly contested, with Tomova's defensive skills and changes of pace drawing Sakkari into a number of extended exchanges. Indeed, it was the WTA No.90 who captured the first break, going up 2-1 as Sakkari leaked a double fault and errors on the forehand and at net.

Day 1: Papamichail, Tsitsipas give Greece 2-0 lead vs. Bulgaria

But Sakkari responded with an immediate break back thanks to aggressive returning, and the pair remained neck-and-neck until the seventh game. After Sakkari had held for 4-3, Tomova required a medical timeout and returned with her lower left leg strapped.

On resumption, the Bulgarian's attempts to shorten the points were a contrast to her earlier successful tactics, and did not pay off. Sakkari broke for 5-3 by quickly tracking down a Tomova dropshot, and then converted her first set point with a forehand winner.

It was the second time in as many days that Team Bulgaria had been afflicted by injury. Like compatriot Isabella Shinikova on Day 1, Tomova continued to compete valiantly -- but through the second set, she was unable to disrupt Sakkari's fine rhythm on serve. The Greek player only conceded three points behind her delivery in the second set, and broke the Tomova serve twice as she sped to victory.

"I was a little nervous in the beginning," said Sakkari. "Especially being 2-0 up in the tie, I knew my match was crucial to winning. She was very solid at first but I found my game, found my serve and everything got better.

"[The United Cup format] is unusual but it's very nice. We get to spend time together, watching each other, so we can learn a lot of things from each other. From the outside you see things differently."

In the next match on RAC Arena, Dimitar Kuzmanov registered Bulgaria’s first United Cup match win as he produced a dominant performance against Greece's Michail Pervolarakis.

Kuzmanov broke his opponent's serve to love in the fourth game of the pair's maiden tour-level meeting and barely looked back from then on. He converted five out of eight break points to race to a 68-minute 6-1, 6-1 victory to lift the spirits of the vocal Bulgarian fans in the stands.

The final match of the tie saw Sakkari return to the court, teaming up with ATP No.4 Stefanos Tsitsipas to defeat Gergana Topalova and Adrian Andreev 6-4, 6-4, thus completing an overall 4-1 victory for Greece.

Sakkari and Tsitsipas, who had previously competed alongside each other at the 2019 Hopman Cup and 2021 Tokyo Olympic Games, asserted their authority by racing out to quick 5-1 leads in each set. But their inexperienced opponents played their loosest tennis with their backs to the wall; in contrast to Sakkari's efficient closing in her singles rubber, she was unable to serve out either set.

Tsitsipas' strong serving had been key to his own Day 1 victory over Grigor Dimitrov, and that weapon came through for Greece again as he closed out both sets on his delivery.

Bulgaria will need to shake off their defeat quickly as they take on Belgium over Saturday and Sunday in a must-win rubber. Greece have two days off before facing Belgium in the final rubber of Group A on Monday and Tuesday.

The ATP Tour contributed to this report.