Paris Saint-Germain midfielder has revealed a part of the team's secret diet which gives them a pre-match boost to improve their performances.
The former Manchester United player has revealed that players at the French club are given a beetroot smoothie before games.
It's said the drink is 'scientifically proven' to improve performance.
The drink seems to be doing the trick for the Parisians this season, as they sit top of the Ligue 1 table - 13 points ahead of Marseille having lost just one game.
Herrera though has revealed that the drink can cause a disturbing surprise and a bit of a fright after the first time they have it.
'When you pee after the game it looks like you're bleeding because it's so strong,' Herrera told futbolemotion as per Marca.
'The first day you say damn, I'm bleeding. But then you remember that you had the beetroot.'
Herrera is not a fan of the drink, despite its supposed advantages in terms of their on-field displays.
He described the drink as 'really disgusting,' before going on to add: 'I think that beetroot is the only thing scientifically proven to improve performance.'
The 32-year-old added in regards to his own personal diet: 'On the days we play, I usually don’t eat breakfast. I eat two meals so I don’t feel heavy before competing.
'Chicken pasta is one of the things I normally eat. During the afternoon if I do know that I am going to be the starter, even if it costs me, I always eat a little more pasta and banana.'
So far this season, Herrera has scored four goals and provided and two assists in 20 appearances for the club.