Make a simple solution of white vinegar, water and baking soda. Mix 1 cup of water and 1 cup of vinegar together, then add in a tablespoon of baking soda. Allow the stained part of the jersey to soak in the mix for at least 30 minutes. You can also use store-bought, presoak treatments to loosen up stains and odors.
https://www.nike.com/a/how-to-wash-a-jersey