A high-quality encounter was decided by a rousing finish from Svitolina, who won five of the last six games to complete a 6-4, 3-6, 6-3 victory.
"I was trying to just focus on my game because Angie is playing really well. She had a terrific year last year and obviously she's pretty confident," Svitolina said in her on-court interview. "I was just trying to fight for every ball."
? WTA (@WTA) January 5, 2017
The pivotal moment came in the eighth game of the final set, Svitolina ending Kerber's resistance to claim the decisive break at the fourth time of asking. Serving for the match, she made no mistake, closing out victory as Kerber sent a backhand sailing wide.
Svitolina is no stranger to big-name upsets, and having also beaten Kerber and Serena Williams in 2016 now has three No.1 wins to her name. By reaching the quarterfinals the Ukrainian guaranteed she will rise to a career-best No.13 in the new rankings, and with few points to defend over the coming weeks she is also well placed to make a charge at the Top 10.
22yo Svitolina has shown steady, quiet improvement year-over-year. 2017 poised to be her breakout season. Steady on. pic.twitter.com/4oCrAVUg4W
? WTA Insider (@WTA_insider) January 5, 2017
Next, Svitolina will face the altogether different challenge of Karolina Pliskova, a 3-6, 6-2, 6-2 winner over Roberta Vinci earlier in the day. "I'm looking forward to it. She's a big server, a big shotmaker - it's going to be interesting."
Kerber, meanwhile, heads to Sydney where she will finalize preparations for the defense of her Australian Open crown. Despite struggling with certain aspects of her game - particularly on serve - the German was keen to accentuate the positives.
"It was still a good match for both of us," she said. "We really played at a high level tonight. I'm happy with my start (to the year). Of course I'm obviously disappointed with how I lost in the quarters.
"I can take the positives out of the tournament."