Halep dominated 2011 's-Hertogenbosch champion and No.1 seed Roberta Vinci in second round play on Wednesday, 60 61. That made the Romanian 3-2 in their series, where each of the matches have been one-sided regardless of the winner.
It has been a series of firsts for Halep lately, reaching her first Premier semifinal last month in Rome, capturing her first WTA title last week in Nürnberg and now having advanced to her first WTA grass court quarterfinal. She has also now won 13 of her past 15 matches going back to Rome qualifying.
"I'm really happy to get a couple of matches in before Wimbledon," Flipkens said. "It feels like a home tournament. It's only a 45-minute to one-hour drive for me. It's really nice because a lot of my friends and family can come.
"I'm very happy because I played at a great level and did what I've been working on all this year," said Muguruza, who is playing her second WTA grass court main draw. "For the first time, I felt very good on grass. In the beginning it was too fast and strange for me because we don't have grass in Spain. But now with last year and this tournament, I'm feeling more comfortable with my game. I think I have a very good game for grass, so I'm getting better each time."