WIMBLEDON, England – It’s been a rough year for Jule Niemeier. She came into Wimbledon with only seven wins -- 18 fewer than her first-round opponent, No.16 seed Karolina Muchova.

Muchova lost to defending champion Iga Swiatek in the Roland Garros final last month and entered the match as a clear favorite, but the 23-year-old German envisioned a different narrative. Niemeier, displaying enormous resilience, upset Muchova 6-4, 5-7, 6-1 in the first round on Thursday.

Wimbledon: Scores | Draws | Order of play

That was one of six first-round matches from the bottom half of the draw, originally scheduled for Tuesday, that were completed two days later after numerous rain delays. To catch up, the winners likely will have to play again Friday and Saturday -- potentially three straight days -- for a chance at a second-week, fourth-round berth.

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Niemeier, a quarterfinalist here a year ago, forged 19 break points in the match and converted four of them -- enough to set up a second-round match with Dalma Galfi, a 6-7 (6), 6-2, 6-2 winner over Linda Noskova. The critical moment came when Niemeier finally won her seventh set point to take the opening frame. Muchova, who needed medical attention in the third set, was suffering from a right thigh injury.

In their only previous meeting, Niemeier defeated Galfi 6-4, 6-2 in the 2021 Prague final.

Bianca Andreescu is ranked No.50 among Hologic WTA Tour players but, as her victory at the 2019 US Open suggests, she is always a potentially dangerous opponent. Anna Bondar can confirm this, after Andreescu kicked off her Wimbledon campaign with a 6-3, 3-6, 6-2 win over the Hungarian.

After a nondescript grass season (2-3, across three events), Andreescu found some rhythm against Bondar. In her fourth appearance at the All England Club, the 23-year-old Canadian advances to the second round for only the second time.

Next up: No.26 Anhelina Kalinina, who defeated Jessica Bouzas Maneiro 6-4, 6-3. Kalinina and Andreescu have never played.

More from Day 4: Rybakina beats Cornet | Andreescu wins; Niemeier knocks out Muchova | Andreeva advances | Garcia edges Fernandez in thriller

In a match suspended by darkness, No.29 Irina-Camelia Begu consolidated on her first-set win and was a 6-2, 3-6, 6-2 winner over Rebecca Marino. Begu next plays Anna Blinkova, who defeated Yanina Wickmayer 6-2, 4-6, 6-3 on Wednesday. The two have never met.

In the other suspended match, qualifier Viktorija Golubic continued her momentum, building on a first-set lead and defeating Anna Karolina Schmiedlova 6-3, 7-6 (4). Golubic converted her fourth match point when Schmiedlova double-faulted to end the match.

Golubic faces No.25 Madison Keys, a 6-0, 6-3 winner over British wild card Sonay Kartal. The Swiss player has won three of four matches against Keys, most notably a 7-6 (3), 6-3 fourth-round victory here at Wimbledon in 2021.