Sport or sports psychologist

I need Your help with grammar since english is not my native language :)

I'm making an award look a like gift for my dear friend but I don't how to name his profession correctly - is it sport psychologist or sports psychologist?

I want to make a card with a sentence "World's best sport/s psychologist".

I've read some articles, book titles; facebook profession option says sport psychologist, while random dictionary goes with sports; it's different everytime, which form is correct? Even here on forum I've found some similar quoestions, but I'd like to know Your opinion about this specific one.

Thanks for Your help!:)

Solution 1:

Sports psychologist.

'Sports' here means 'relating to sport'. So, in this case, it isn't the plural of sport but an adjective (Cambridge Dictionary online).

Many other constructions follow the same pattern: sports journalist, sports teams, sports event, etc.

For better understanding (hopefuly), an unusual way to reword it would be 'sporting psychologist', where sporting also means 'relating to sport' (same reference), though maybe it wouldn't be so odd, since 'sporting journalist' is not entirely uncommon.