Johanna Heldin/Daniel Magnusson (Uppsala, SWE) won 8-5 over Adela Walczak/Andrzej Augustyniak (Lodz, POL) in the Final of the Oberstdorf International Mixed Doubles Cup, held September 3 - 5, 2021 in Oberstdorf, Germany. To advance to the championship game, Heldin/Magnusson won 9-8 over Zuzanna Rybicka/Bartosz Dzikowski (Lodz, POL) in the semifinals of the 2021 Oberstdorf International Mixed Doubles Cup in Oberstdorf, Germany; and won 8-4 over Marie Kaldvee/Harri Lill (Tallinn, EST) in the quarterfinals. of the 2021 Oberstdorf International Mixed Doubles Cup in Oberstdorf, Germany;
 
Heldin/Magnusson finished 3-1 in the 16-team qualifying round. . In their opening game, Heldin/Magnusson defeated Nina Summerova/Jan Horacek (Bratislava, SVK) 10-1, then won 8-3 against Lea Hueppi/Jonas Weiss (Kusnacht, SUI). Heldin/Magnusson went on to lose 10-1 against Oihane Unanue/Mikel Unanue (San-Sebastian, ESP). Heldin/Magnusson responded with a 7-6 win over Rybicka/Dzikowski in their final qualifying round match.
 
. For week 6 of the event schedule, Heldin/Magnusson did not improve upon their best events, remaining at 778th place on the World Ranking Standings with 74.592 total points. Heldin/Magnusson ranks 294th overall on the Year-to-Date rankings with 0.000 points earned so far this season.