Maria Sakkari sealed Greece's spot in the United Cup quarterfinals after saving four set points in the first set and coming from 3-1 down in the second to defeat Leylah Fernandez 7-6(2), 6-3 in Sydney.

Earlier, Stefanos Tsitsipas had made a successful start to his 2024 singles season on Wednesday when he defeated Steven Diez 6-2, 6-3 to give Greece a 1-0 lead over Canada.

To clinch a quarterfinal place, Greece needed to either defeat Canada 3-0, or 2-1 if the sets score is not 4-4. Straight-sets wins by Tsitsipas and Sakkari mean that Canada is no longer able to win four sets in the rubber.

In the Sydney quarterfinals, Greece will take on Germany while France will face Norway.

Sakkari ultimately captured her third straight-sets win against Fernandez in as many meetings, but had to work especially hard this time round -- particularly in a marathon opening set. Nine of its 12 regular games featured at least one deuce, and Sakkari's clutch performance on key points was crucial.

The WTA World No.8 fell behind 2-0, but immediately broke back and saved five out of the six break points she faced in the set. Fernandez, the 2021 US Open finalist, placed Sakkari under continuous pressure with skilful baseline redirections and delicate drop shots, but the Greek player was able to find some of her strongest serves when she needed them.

This was particularly the case in a six-deuce ninth game, in which Sakkari had to fend off four set points. Fernandez will rue a timid volley on the first, which allowed Sakkari to pass her easily; however, Sakkari saved the remainder with powerful play of her own before closing out the game with consecutive unreturned serves. The 28-year-old took her momentum into a dominant tiebreak, ultimately winning 11 of the last 13 points of the set.

As in the first set, Fernandez went up an early break in the second. But Sakkari responded in style, reeling off five straight games from 3-1 down to seal the win. The 2023 Guadalajara champion found some of her best shots during the home stretch, ending a terrific offensive rally at net to break back for 3-3 and then breaking Fernandez again for 5-3 by blitzing a forehand winner down the line.

ATP World No.6 Tsitsipas did not play singles in his country's tie Tuesday against Chile due to concerns over his back. But after playing the mixed doubles, he returned to singles action inside Ken Rosewall Arena.

Asked about the strong Greek support he received, Tsitsipas said, "Athens, Sydney, it doesn't make much difference right now. I am out here enjoying playing tennis. There is a lot of blue and white around the stadium, which happen to be my favourite colours.

"Today was a good summary of how aggressive I can be. I'm always seeking extra credibility in my game and whatever I can add to my game I am always willing and open-minded.

“I always have a lot of energy when I'm playing in Australia, which keeps my blood pumping.”

It was Diez who struggled physically in the match, receiving a medical timeout in the first set. Tsitsipas dominated on serve, saving the only break point he faced to triumph after one hour and 18 minutes.

According to Infosys ATP Stats, Tsitsipas won 90 per cent of his first-serve points and broke serve three times from six chances. He hit six aces in his first Lexus ATP Head2Head meeting with World No. 314 Diez.