The teenager, who was a wildcard at the event, defeated World No.10 Aryna Sabalenka 7-6(3), 1-6, 6-4.

"I think it was all mental," Aiava said after the match.

"It was a really long and tough match. I knew going into the match that it was going to be a big challenge.

"Going into it, I just wanted to go for it and not waste the wildcard that the tournament gave me.

"I just wanted to take this opportunity and use it."

Earlier this year, the world No.214 beat former Top 10 player Kristina Mladenovic at the Brisbane International.

The win in the Netherlands is just the third WTA main-draw victory in Aiava's career.

She will next face Russian Veronika Kudermetova for a spot in her first career WTA quarterfinal on June 12 (local time).