MELBOURNE, Australia -- Former World No.1 Garbiñe Muguruza of Spain pulled off a stunning comeback in the first round of the Australian Open on Tuesday, shaking off a first-set bagel and a medical timeout to overcome American qualifier Shelby Rogers, 0-6, 6-1, 6-0.

Two-time Grand Slam champion Muguruza, whose best result at Melbourne was a quarterfinal showing in 2017, had beaten Rogers in the second round of Shenzhen two weeks ago, and engineered an incredible fight to pick up another win over the American this season in an hour and 34 minutes.

"Today out there, well, it was a very tough performance because I wasn't feeling at my best at all," Muguruza said, in her post-match press conference. "But at the end I could manage to give my fight. Happy that I came back [after] that tough first set."

In the topsy-turvy match between hard-hitting players, Muguruza finished with 20 winners to Rogers’ 15, as she reeled off 12 of the last 13 games of the encounter after being blitzed in the first set.

"It was a tough moment because, you know, [Rogers] was playing great," said Muguruza. "When you're not feeling well, you sometimes don't know how to turn things around. You know, I said to myself, 'Hey, you're here, you're on the court, you're playing Australian Open, it's a special moment, so just hang in there and keep fighting.' At least she has to play very good the entire match.

"I stayed behind her. You know, today I won the battle."

The Spaniard had withdrawn from Hobart with a viral illness last week, and she got a visit from the trainer after falling behind 0-5 in the opening frame. Rogers had no trouble continuing her winning powerful play in the next game, as she thundered a superb service game for a love hold and a 6-0 lead.

However, Muguruza shook off that set to find forehand ferocity and get on the board in the first game of the second set. Suddenly, the Muguruza groundstroke greatness increased, as did the number of Rogers unforced errors, and the Spaniard built a commanding lead in the set. At 5-1, Muguruza closed out a love service hold with two straight aces, and she had leveled the match.

Now fully in flight, Muguruza motored through the decider, blasting eight winners and never facing a break point. The American, meanwhile, was undone by 13 unforced errors as her pristine first-set form had dissipated.

One final fierce forehand by Muguruza closed out the affair in her favor after facing a dire deficit. The Spanish No.1 will now face a home favorite on Thursday when she takes on another power hitter, Top 50 player Ajla Tomljanovic, in the second round.

Meanwhile, in the biggest upset of the tournament thus far, Tunisia's Ons Jabeur knocked out No.12 seed Johanna Konta of Great Britain, 6-4, 6-2, in just over an hour.

Jabeur fired 19 winners past her opponent, who could only manage eight all day, and the Tunisian converted four of her six break points to ease by the Brit. The wily Jabeur was spectacular behind her second serve, winning two-thirds of those points en route to a Top 20 win.

Konta was playing just her second match since the US Open in August, as she continues a comeback from a knee injury. The former World No.4, who reached the semifinals of Roland Garros and the quarterfinals of Wimbledon and the US Open last season, was undone by 19 unforced errors, but was optimistic about her recovery.

“I think giving myself that time to find a level that I want to play is going to be important, and, yeah, I also played a very good opponent,” Konta said with a smile during post-match press.

“It's always difficult to come back after not playing a certain amount of time,” Konta added. “But what was good today was my knee felt quite good, and it was actually even better than Brisbane. That's a very positive thing for me, especially for where I was in September.”

Jabeur has now reached the second round of all four Grand Slam events in her career. The World No.85 will now face a former World No.4 for the second straight match: France’s Caroline Garcia, who overcame Madison Brengle of the United States, 6-7(5), 6-2, 6-2.

No.18 seed Alison Riske of the United States had a much tougher path to the second round, as the American overcame China’s Wang Yafan, 7-6(5), 2-6, 6-3, in three hours spread over two days.

Riske, who made her Top 20 debut at the end of last year, squeaked out the first set in a tiebreak before Monday’s rain forced the conclusion of the match to the next day. Upon resumption, Wang blew through the second set before Riske regrouped to close out the decider with two consecutive winners, out of her 45 in the match.

A number of other seeds clinched straight-set first-round victories. No.22 seed Maria Sakkari of Greece dispatched Russia’s Margarita Gasparyan, 6-2, 6-2, and No.27 seed Wang Qiang of China moved past French wildcard Pauline Parmentier, 7-6(2), 6-3.

No.29 seed Elena Rybakina of Kazakhstan improved to 10-1 on the season with a 6-3, 6-2 victory over American Bernarda Pera. Rybakina reached the Shenzhen final in the first week of the season, then claimed the Hobart title last week as the 20-year-old’s rapid rise in the rankings shows no sign of stopping.

Also, last week’s Adelaide runner-up Dayana Yastremska of Ukraine, the No.23 seed, cruised into the second round with a 6-1, 6-1 win over Slovenian qualifier Kaja Juvan. Yastremska never faced a break point in her 54-minute triumph.

But No.21 seed Amanda Anisimova of the United States was stunned by Kazakhstan's Zarina Diyas, 6-3, 4-6, 6-3, in a one-hour and 46-minute upset. Anisimova's 45 winners tripled Diyas's total, but the American teenager fired 62 unforced errors, well outpacing Diyas's 19 miscues.

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