SYDNEY, Australia - No.2 seed Angelique Kerber maintained her supremacy over Camila Giorgi at the Sydney International - though her fourth win in as many meetings with her unseeded opponent, an engrossing 7-6(3), 6-2 tilt, did not come easily by any means.

For the second year running, Kerber came into Sydney having been one of the Hopman Cup MVPs. Partnering Alexander Zverev, the Wimbledon champion had gone unbeaten in four matches against Garbiñe Muguruza, Alizé Cornet, Ashleigh Barty and Belinda Bencic as she carried Germany all the way to the final - where she also impressed in the deciding mixed doubles rubber, lighting up social media with a spectacular forehand-to-forehand duel against Roger Federer.

But in a rematch of last year's semifinal, won by Kerber 6-3, 6-2, the 30-year-old was far from her best, struggling with a 44% first serve percentage in the opening set. Giorgi, as ever, did not hold back: the Italian cracked 22 winners in the first set and 34 overall, and in the initial stages was particularly sharp in following up her lightning groundstrokes with deft play at net.

This form enabled Giorgi to leap out to a 3-1 lead, but in what would become a pattern, four consecutive backhand errors would evaporate her advantage immediately as Kerber broke back to love. The World No.27 would nonetheless often look the more dynamic player as the tightly contested set drew on - but it is quintessential Kerber to keep the scoreline close in these scenarios while quietly, gradually tightening up her game. 

As the set headed towards a tiebreak, there were signs that Kerber was beginning to read Giorgi's notoriously unpredictable patterns of attack, defending better against the Linz champion's barrage and spreading forehands of her own around the court when she got the chance. And once the tiebreak was under way, all of the former World No.1's experience came to the fore as Giorgi collapsed, offering up two double faults and three unforced errors to dig herself a 0-5 hole.

Two spectacular Giorgi drive volleys were too little, too late at that juncture as Kerber sealed the set with an unreturnable serve on her first set point.

A similar story played out in miniature across the second set. Giorgi conjured up three breathtaking backhands to seize the first break for 2-1 - but with the Kerber forehand also now firing, the lead was again pegged back immediately.

As Kerber held for 3-2, asserting her status with her most aggressive game of the match, there was a sense that the pendulum had swung for the final time. Even two mini rain delays couldn't halt the Kerber momentum as the three-time Grand Slam champion reeled off the final five games of the match. Giorgi, naturally, swung for the fences until the end, saving one match point with a blistering backhand winner on the line - but her 39th unforced error of the day on the next point sealed victory for Kerber.

The World No.2's reward will be a quarterfinal at one extreme or the other: she will face either No.5 seed Petra Kvitova in another match-up against relentless power - or the paceless art and craft of Hsieh Su-Wei in a rematch of last year's excellent three-set Australian Open fourth-rounder.