AUCKLAND, New Zealand - Laura Siegemund came back from a set down to end 15-year-old Coco Gauff’s run at the ASB Classic and book her spot in the quarterfinals. 

The German dropped a tightly-contested opening set, but never deviated from her game plan of mixing up the rhythm with her crafty forehand slices and dropshots. Siegemund struck 27 winners and broke Gauff eight times en route to a 5-7, 6-2, 6-3 victory. 

"I think I had a really good start in the first set, or the first set in total, except for the last four games," Siegemund said after the match. "I was up 5-3...and I had problems serving that set out, so that was a little bit unfortunately, but she also played well. 

"I knew I was playing a good level and I just needed to keep it up, and not get frustrated with losing the first set after that lead."

Siegemund, currently ranked World No.73 but once as high as No.27, finished her 2019 season with a semifinal showing at Bucharest and pair of quarterfinals in Hiroshima and Luxembourg. It was a solid display from the 31-year-old, who suffered a terrible right knee injury in 2017 - her breakout season - and has struggled to regain her world-beating form. 

Vexing her opponents with her wicked forehand slices and ability to change the pace of a rally, Siegemund has earned reputation as a tricky opponent, and she employed all of her range against Gauff on Auckland’s Stadium Court. 

But it was Gauff who claimed the opening set, despite trailing by a break down twice. Siegemund got on the scoreboard early with a break at 1-0, but Gauff fought her way back to level at 2-2. Siegemund surged ahead again at 4-3, consolidating to 5-3, but Gauff adjusted her game and reeled off four games in a row, leveling at 5-5 and taking the set 7-5. 

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The second set saw the serving player win just two games as the pair combined for six breaks of serve. Both times it was Siegemund who came out on top, with two confident love holds at 3-1 and 6-2 turning around the match in her favor as an increasingly frustrated Gauff struggled with her ball toss in the windy conditions.

"I was looking forward to having a couple of matches here. You never know how you're going to get on in the sprint out of the blocks... and I'm happy with my first performances of the year," she added.

"It's good to play against big names. I was happy to also play against Gauff today because those are the kinds of matches, situations that you want before a Slam -- with the audience, the atmosphere and the crowd being into it, so I'm happy for this match."

Gauff’s service woes continued in the final set. Fully dialled in, Siegemund peppered in some dropshots to keep Gauff on her toes, and recorded a break at 2-1 to take the lead. She continued to employ her variety against the American, and a second break in the final game wrapped up the match after a hard-fought two hours and 14 minutes to advance past the first round of the ASB Classic for the first time. 

Into her first quarterfinal of the year, Siegemund will match wits against top seed Serena Williams, who rallied from a set down to beat compatriot Christina McHale in the second round. 

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"I've been playing solid and aggressive, which I like to see from me," Siegemund continued. "Against Serena, the whole thing is a little bit of a different story, but on the other hand, but you know who you're playing against.

"I watched her match today and we've played also before, so you have to also stay with your game. I have nothing to lose. She's a great player and a legend, and I think I can go out and enjoy the moment, try my best, and hopefully do some damage."

2020 Auckland Highlights: Siegemund battles past Gauff