The Spanish top seed got back into the match by breaking to lead 4-2 in the second set, but lost the next four games.

Defending champion Petra Kvitova powered past Daria Gavrilova 6-2 6-2 to reach the quarter-finals.

The Czech next faces Julia Gorges, who beat Ashleigh Barty 7-6 (8-6) 6-3.

German fifth seed Gorges saw off Australia's Barty, who won last week's Nature Valley Open in Nottingham.

No Wimbledon worries for Muguruza

Muguruza put in an error-strewn performance against Strycova

World number three Muguruza made 29 unforced errors against world number 24 Strycova, who said she needed to play her "best tennis" to win.

But Muguruza, who lost only one set on her way to the Wimbledon title last year, says her preparations are on track for this year's tournament, which starts on 2 July.

"Barbora plays very good on grass. Her style of game suits very good the surface," the 24-year-old said.

"I wish I would play more matches, but nothing really worries me. We have a lot of time now to prepare [for Wimbledon]. In a way it's good."

Strycova will play Ukrainian Lesia Tsurenko for a place in the semi-finals after the world number 34 beat Russian sixth seed Daria Kasatkina 1-6 6-3 6-3.

Kvitova shows her intent before Wimbledon

In windy conditions, Kvitova raced into a 4-0 lead in the first set before being pegged back by Gavrilova in a match lasting almost one hour 20 minutes.

The two-time Wimbledon champion sealed victory on her first match point when the Australian world number 25 fluffed a smash.

"A few of the games were very tight, especially when you need to break. It's always tough to get the break on the grass," said Kvitova.

"The grass helped me, for sure. That's my surface. It was great."

Kvitova, who has won four WTA titles in 2018 - more than any other player - played some powerful backhands but served five double faults.

"There's still a few things I can improve - the serve, probably. You need to serve well on the grass," she said.