Barcelona suffered a first defeat since their 2021/22 Champions League final loss to Lyon, as they were beaten 3-1 by Bayern Munich at the Allianz Arena on Wednesday.
Roared on by a crowd of 24,000 - a record home attendance for a Bayern Munich Women's match - the hosts found themselves 2-0 up inside 10 minutes thanks to goals from Klara Buhl and Lina Magull, as Barça failed to deal with a pair of crossed from either flank.
Lea Schuller added a third in the second half, before Geyse netted what would prove to only be a consolation for the visitors.
The result leaves Bayern level on points with Barcelona at the top of Group D with two group stage matches remaining - although the Spanish champions do have a superior goal difference.
Barcelona had eventually ran out comfortable 3-0 winners when the two sides met at Camp Nou a fortnight ago after patiently breaking down a stubborn Bayern. However, they were stunned inside four minutes as Buhl opened the scoring, turning home Sydney Lohmann's cross from the right via a deflection off Irene Paredes.
Six minutes later it was two, Schuller providing the surge of pace and delivery from the left, and Magull providing the first time finish.
The pair combined again as Bayern added a third on the hour mark, Schuller rising highest to power home a header following Magull's deep, looping cross.
La Blaugrana pulled one back with 25 minutes remaining, Geyse charging down goalkeeper Maria Luisa Grohs, winning back possession and stroking into an empty net
They then pushed for a second goal but could find no way past a resilient Bayern, digging in to secure a famous victory.