But the Croatian collapsed once the match resumed on Court One on Thursday and Pella took full advantage to set up a third round clash with Mackenzie McDonald of the United States. The Belgian, who has been open about her relationship on social media, talked about it publicly for the first time in a segment of a television sports show back home earlier in the year, where she said the couple were going to live together soon.
In the men's event, third seed and last year's runner-up Marin Cilic was knocked out by Argentina's Guido Pella.
Top seed and French Open champion Simona Halep, however, reached the third round with a 7-5, 6-0 win over China's Zheng Saisai. Everything was just coming together for me.
American Liu, 18, won the first set before the 2016 finalist came back to win 3-6 6-2 6-4.
Van Uytvanck beat No. 3 seed Muguruza in straight sets, 7-5 2-6 1-6.
But considering that as of Wednesday, five of the top-10 seeds in the women's draw were spending the remainder of the fortnight preparing for the hard-court season, no match at Wimbledon, no matter the round nor tale of the tape, is a foregone conclusion. You always want that first game, you know.
"When I'm done practicing I go to my house, play video games".
When Garbine Muguruza clutched her temple with both hands and shook her head repeatedly, she laid bare the throbbing pain racing through her body as her Wimbledon title defence was hijacked by a little-known Belgian on Thursday.
Unseeded American Taylor Fritz, 20, has taken a two-sets-to-one lead over Germany's fourth seed Alexander Zverev in Wimbledon's second round, in a match suspended by darkness.
The 23-year-old Jabeur, whose best Grand Slam result was making the third round last year at the French Open, dropped serve seven times from eight break points faced against Siniakova. "It's a little bit sad... but she played great". There's nothing I can do.to say something now makes no sense.
In the only other upset on the day veteran Dominika Cibulkova sent No. 22-seeded Brit Johanna Konta out of the tournament 6-3, 6-4. "I'm happy", said Van Uytvanck, the world number 47.
"I was just not feeling as comfortable as yesterday with hitting", he said.
Meanwhile, Ekaterina Makarova of Russian Federation has become the first player to reach the fourth round at Wimbledon. "I'm happy to be through, I think I played much better today".
The Australian, who won the girls' title in 2011, beat the 2012 champion 6-4, 7-5.