SYDNEY, Australia -- In a bruising encounter between two of the WTA's hardest hitters, Italian qualifier Camila Giorgi ousted 2015 Sydney International champion Petra Kvitova, 7-6(7), 6-2, to advance to the quarterfinals of the 2018 edition of the tournament.

The World No.100 has not yet dropped a set through three rounds of qualifying and two main draw rounds, the last two of which not only includes her win over Kvitova, the 2011 and 2014 Wimbledon champion, but also her first round victory over reigning US Open champion Sloane Stephens.

Giorgi knotted her record with Kvitova at 1-1, after the Czech had won their only other meeting in straight sets at the Fed Cup in 2014. Giorgi kept her explosive game in high gear today with superlative returns, and surprisingly winning a higher percentage of first service points than Kvitova (59 percent to 55 percent). Kvitova was also undone by 34 unforced errors in the match, ten more than the equally go-for-broke Italian.

The opening stanzas of the match went easily with serve, as both players were handling their delivery exceptionally well, and barely losing points when they stepped to the line. Only seven points were won by the returner in the first seven games.

Kvitova was the first to wobble serving down 3-4, as Giorgi started to hit absurdly strong and effective returns, and focused on breaking down the Czech’s backhand as best as she could. Nevertheless, Kvitova was able to survive four break points to hold for 4-4.

The Czech former World No.2 faced an even more precarious service game in her next go, as Giorgi continued to take extreme risks on her return of serve. One such return clipped the net and barely dribbled over to give Giorgi her first set point. After it was saved, Kvitova hit her first two double faults of the match to give Giorgi two more set points, but those were fended off as well. Kvitova finally held for 5-5 after an eight-minute game.

After failing to convert any of her seven break points, Giorgi cracked at 5-5. An overrule on the baseline by chair umpire Aurelie Tourte rattled Giorgi, and she lost two straight points after that to give Kvitova a 6-5 lead on the Czech’s first break opportunity of the match.

Suddenly, Kvitova was serving for the set. But she could not close out the opener, hitting her third double fault in two games, and then being unable to successfully respond to a powerful Giorgi backhand when down break point.

The players moved into the tiebreak, and Giorgi took an early 3-1 lead. Two unreturnable serves by Kvitova, however, put her in front at 4-3. After repelling three set points earlier in the set, Kvitova finally reached her own set point at 6-5. Giorgi was unfazed, and hit a fine serve that Kvitova could not return into play, which deadlocked the tiebreak at 6-6.

A forehand winner by Kvitova saved a fourth Giorgi set point to level the breaker at 7-7, but Giorgi claimed the crucial mini-break on the next point by dragging Kvitova wide and tempting the Czech into a forehand error. One final error long by the usually fearsome Kvitova forehand gave Giorgi the first set on the Italian’s fifth set point, after a grueling 70 minutes.

The second set, by comparison, was anticlimactic, as the wind went out of Kvitova’s sails. Giorgi started to step way into the court on second service returns, and Kvitova’s forehand faltered much more often than it does during her purple patches of form.

Kvitova threw in a fatigued double fault down break point at 1-1 to give Giorgi the first lead of the second set. Then, serving at 4-2, Kvitova was broken at love after she hit multiple forehands wide with no provocation.

Giorgi neared the finish line, and serving at 5-2, 30-30, the Italian hit an ace to bring up her first match point. Here, Kvitova put up her sternest resistance of the set, saving four match points, but the Czech could never reach break point in an attempt to extend the match any further.

A lovely backhand winner by Giorgi brought up a fifth match point, and one more wide unforced error from the Kvitova forehand gave the qualifier another straight-set win in a long line of them this week.

Giorgi will face another previous champion in Sydney, 2013 titlist Agnieszka Radwanska, in the final eight, after Radwanska dispatched CiCi Bellis earlier on Wednesday. Radwanska beat Giorgi en route to her run to the Wimbledon final in 2012, but Giorgi tied their head-to-head at one match apiece in 2015 with a semifinal victory in front of Radwanska's home crowd in Katowice.

More to follow...