What dua do I say before a competition?

Musa's dua for a hard task

When Allah sent Musa (Moses) to face Pharaoh, he asked for an open heart and an easy path. Muslims use these words before exams, interviews, speeches and big games:

He continued: "Wa yassir li amri" (and ease for me my task), and asked Allah to untie the knot from his tongue (Quran 20:26–27). Say it in the changing room or while warming up.

Duas for nerves and trust

• Hasbunallahu wa ni'mal wakil ("Allah is enough for us, and He is the best disposer of affairs"), the words of the believers when they were under pressure:

• Against worry and weakness: "Allahumma inni a'udhu bika minal-hammi wal-hazan, wal-'ajzi wal-kasal" (O Allah, I seek refuge in You from worry and grief, from helplessness and laziness). The Prophet ﷺ often said this (Sahih al-Bukhari 6369). See What dua can I say when I feel anxious?
• For ease: "Allahumma la sahla illa ma ja'altahu sahla" (O Allah, nothing is easy except what You make easy), a well-known dua reported in hadith collections.

Your own words are fine too

You can ask Allah in English: "Ya Allah, help me play my best, keep everyone safe, and keep my heart humble whether I win or lose." See Can I make dua in my own words? It's also fine to ask Allah for the win itself, as long as you accept His decision.

Prepare, then trust

Dua doesn't replace training. The Prophet ﷺ told a man to tie his camel and then trust in Allah (Jami' at-Tirmidhi 2517). He also said: be keen on what benefits you, seek Allah's help and don't give up, and if something goes wrong, don't say "if only," but say "Allah decreed it and did what He willed" (Sahih Muslim 2664). That's a perfect mindset after a loss. See Does tawakkul mean I shouldn't worry?