Osaka, 21, won 4-6 6-3 6-4 to reach the last eight for the first time in Melbourne.
“I wasn’t really sure what to do at a certain point, but I just tried to stick in there," Osaka said. "I was thinking I’ve been in this position before, and I was watching all these kids winning – seeing Tsitsipas beat Federer - so I decided I wanted to do well too.”
WTA Miami, FL
Federer, Williams, Osaka scheduled to play stacked Miami Open
The 2018 US Open champion, targeting back-to-back Grand Slam victories, currently trails Svitolina 3-2 in their head to head, having lost both hard-court encounters against the Ukrainian in straight sets last year in Dubai and Miami.
Osaka completes another comeback victory to beat Sevastova
Sevastova edged ahead in the first set after converting her first break point, and closed out the opener without offering Osaka a single opportunity to break back.
The second set saw Osaka save a break point on her way to moving 5-2 in front, and the Japanese saved another before eventually forcing the decider.
Osaka took that momentum with her, breaking immediately, but she was pegged back in the sixth game with Sevastova requiring six break points to level at 3-3.
Sevastova surrendered her serve straight away, however, and Osaka then survived eight deuces in the eighth game before seeing it out two games later.
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