The 14th seed is coached by Conchita Martinez, the only Spanish player to have claimed the women's singles title at Wimbledon when she won in 1994.
Ostapenko confirmed her status as one of the rising stars of the women's game when she earned a surprise victory at Roland Garros last month. Magdalena Rybarikova, a Slovakian ranked 87th, reached her first quarterfinal in 36 Grand Slam tournaments. Muguruza saw her chance to play her third Grand Slam quarterfinal as she went leading by a set and a break.
10 seed, made her debut in the grasscourt major back in 1997.
Ostapenko advanced to her first Wimbledon quarterfinal after converting her eighth match point to beat Elina Svitolina 6-3, 7-6 (8-6).
Williams secured an early break in the second set but a double-fault allowed Ostapenko to break back and briefly the Latvian livewire looked unsafe with some bludgeoning winners.
Asked what it was like without Serena and her dad, Venus said: "They're definitely here with me, for sure".
All England Club chief executive Richard Lewis said scheduling decisions involve "some hard choices". "It was great preparation for me to be able to get used to that sort of pace", Venus said of facing Konjuh's big-hitting, all-or-nothing style of tennis. Their matches were all on the tournament's two principal courts. So far these two players have played only one match.
"I wouldn't say it's favoritism", Lewis said. "It's not about male or female, in the end it's about which matches you feel the public and broadcasters want to see". He also fared better on his own serve, finishing with 23 aces, an unusually high total for Nadal and only seven fewer than Muller.
But the Latvian really did start to make her mark in the second set, cutting down on the errors and testing the Williams movement and stamina with her big serving and drives to the corners of the court.
But the Romanian's gut-wrenching 6-7 (2-7) 7-6 (7-5) 6-4 loss to Konta instead leaves Czech Karolina Pliskova celebrating her career-first climb to the summit.
Britain's last female champion was Virginia Wade in 1977.
With pregnant younger sister Serena skipping Wimbledon, Venus has been in the headlines on and off the court.
The 37-year-old has not won a grand slam crown since lifting the Venus Rosewater Dish for the fifth time nine years ago.
The other women's quarterfinal matchups Tuesday: Konta vs.
She'll face the victor of the next match on Centre - Simona Halep's contest with Jo Konta.
But Centre Court routinely takes two of its three daily matches from the men's draw, leaving some prominent female players feeling overlooked.
"I could hear [it], it was pretty clear because we all speak Spanish", said the Russian. "Also for the spectators, it's more enjoyable to watch, because it's".