What's the wet patch on footballers' chests?

Try The Athletic for FREE for 30 days: https://theathletic.com/tifofootball 📗 Tifo's new book, "How to Watch Football" is now available internationally: https://linktr.ee/tifobook Have you noticed that some footballers have a wet patch on their chest? Let’s explain what it is. Follow Tifo Football by The Athletic: Twitter: https://twitter.com/TifoFootball_ Facebook: http://facebook.com/TifoFootball Instagram: http:/...