[3] In November 2020, he competed in the European Junior Championships and won the bronze medal in the boys’ singles.

[13] Earlier in the same year, he had also played against Denmark's Viktor Axelsen (11–21, 13–21) in the European Mixed Team Championships.

[15][16] He secured his second victory in the Estonian International in Tallinn in January 2024 against Danylo Bosniukin in the final (21–5, 21–13).

[17][18][19] Oldorff's first runner-up position was secured in September 2023 when playing in the Belgian International tournament final.

[22] Oldorff won bronze at European Championships in Saarbrücken by beating Alex Lanier in the quarter finals (21–12, 21–19), and then facing Anders Antonsen in the semifinals (11–21, 11–21).