Osorio Serrano won through 5-7, 6-3, 6-2 in a stunning display for her first top 10 victory.
The 19-year-old emerged earlier this year on clay by winning in Bogota on the WTA Tour for her first title and will hope to replicate that on the hard courts this week.
It was a match that started yesterday with Svitolina leading 7-5, play was suspended due to inadequete light. This proved to thwart the Ukrainian with Osorio Serrano returning for 6-3, 6-2.
In particular, she came from 0-2 down in the second to produce an aggressive baseline display and defy Svitolina throughout the conclusion.
Mayar Sherif awaits tomorrow for a place in the Quarter-Finals in Spain.