In May 2018, Duda won the Polish Chess Championship with a score of 6½/9 (+4–0=5), a full point ahead of runner-up Kacper Piorun. He recorded victories over Piorun, Radosław Wojtaszek, Daniel Sadzikowski, and Aleksander Miśta. In July 2018, he became the No. 1 ranked Polish player and the No. 1 ranked junior in the world, outstripping Wojtaszek and Wei Yi, respectively.
