SYDNEY, Australia - Angelique Kerber remains unbeaten in 2018 after eking out a high-quality contest between unseeded former Top 5 players, defeating Lucie Safarova 6-7(3), 7-6(6), 6-2 in two hours and 28 minutes to move into the second round of the Sydney International.

"I think we had everything," said the German afterwards. "We had the heat, we had the rain, we had everything."

Kerber had not beaten her opponent today in half a decade, and trailed 1-2 in their overall meetings. But at last week's Hopman Cup in Perth, Kerber had overcome negative head-to-heads to best two other rivals, Belinda Bencic and Eugenie Bouchard, en route to helping Germany reach the final of the team competition. Indeed, she had been the only player in the event not to drop a set in singles - a performance that indicated a return to form for the 2016 Australian Open champion, who had fallen out of the Top 20 last year.

"I say goodbye to 2017, for sure," she laughed afterwards. "I really try to forget the year and start from zero, and just play like I played years before 2017... I just feel that I'm playing every single point again, and I have the patience back and really fighting again. I'm not thinking too much like I was thinking in the last 12 months."

So, yeah, I'm feeling good. I'm trying to changing a few things and I'm starting 2018 with completely new mind and just going for it, and having matches like this that gives me of course a lot of confidence, and also like I played in Perth.

But Safarova demonstrated in the first set exactly why she has been such tough opposition for Kerber, nullifying the advantage of the World No.22's left-handed forehand with her own bullet of a stroke. Time and again, the 30-year-old combined unreturnable power with phenomenal accuracy, rifling the ball into the corners of the court and notching up 47 winners in total. Furthermore, the success Safarova was finding with her relentless first-strike style was forcing Kerber to take a similar approach just to keep up.

In a set that featured six breaks of serve, neither player managed to seize a lead of more than one game. The second service was key: Safarova was winning 67% of her first serve points, and Kerber 62% of hers, but those percentages would drop to just 33% and 25% respectively behind the two players' second deliveries. With a marginally higher first serve percentage, it made sense that the Czech would capture the inevitable tiebreak - which she did with a ferocious return that landed on the baseline at Kerber's feet, eliciting an error from the outgunned 29-year-old.

Neither a break for a sudden thunderstorm at 6-5 in the first set nor a second due to the threat of lightning just three points into the second set bothered Safarova: the 30-year-old continued to deliver sturm und drang of her own with booming down-the-line winners, and was the first to draw blood as she broke for 2-1. But Kerber immediately retaliated, upping the pace on her own returns and matching Safarova for accuracy and aggression: first-strike may not be her natural style, but the former World No.1 proved that she can certainly hang with it, striking 31 winners of her own over the course of the match.

The second set also saw Kerber raise her first serve percentage from 62% to 78%. "I think at the end my serve was the key for me," she acknowledged afterwards. "And also that I was able to [go] for it in important moments when I had the break chance."

Indeed, in contrast to the first set, there were to be no further break points as the two players made their way to another tiebreak, repeatedly staving off moments of potential danger with strong serving while finding success in rallies of fine margins.

The ensuing tiebreak took a turn for the shaky, though: wild Safarova errors gave Kerber the advantage, but the 2014 runner-up's serve had regressed. From set point up, consecutive double faults put Kerber match point down - but that was saved thanks to emerging on top of a grinding rally, and two points later a service winner would save a second. Safarova, unable to stem her mistakes, sent a backhand into the net on her opponent's second set point.

As the thrilling match headed into a third hour, Kerber was playing with increasing energy and freedom, extending more and more rallies - just how she likes to play the sport. The third game of the decider was key, featuring some of the most high-quality shotmaking of the day: a flicked Safarova forehand angle, Kerber relentlessly out-manouevring her opponent with smart shot selection. When the German triumphed on her third break point, it would prove crucial. She would concede just four further points on serve in a dominant finish, setting up a second round against No.2 seed Venus Williams after two hours and 28 minutes.

The last time Kerber defeated Safarova was also in the first round of a Premier event, in Paris in 2012, and she would go on to win the entire tournament - her first title of 10 to date. In her current form, it would be unwise to bet against the pattern repeating.