In a stunning upset at the Berlin Open, German qualifier Jule Niemeier defeated defending champion Ons Jabeur 7-6 (4), 6-4 in the first round. Niemeier, ranked 120th, saved two set points while trailing 5-3 in the first set and then dominated the tiebreaker, winning the final four points. She carried this momentum into the second set, breaking Jabeur's serve in the opening game and maintaining her advantage to secure the victory in 1 hour and 35 minutes. This marks Niemeier's third career win against a top-10 opponent.

In other matches, American teenager Coco Gauff notched her 23rd win of the year, defeating Katerina Siniakova 6-3, 6-4. Gauff will now face Ekaterina Alexandrova, who advanced by defeating Liudmila Samsonova 6-4, 6-3.

Top-seeded Aryna Sabalenka cruised into the second round with a comfortable 6-3, 6-2 win over veteran Vera Zvonareva. Sabalenka capitalized on three of her nine break point opportunities, while Zvonareva, a 2010 Wimbledon finalist, was unable to convert any. Sabalenka's next opponent will be either Veronika Kudermetova or Zheng Qinwen.

Elina Avanesyan staged a comeback victory, saving two match points to defeat sixth-seeded Daria Kasatkina 6-2, 3-6, 7-6 (7). Avanesyan will now face fellow Russian Anna Blinkova in the next round.