The pair will be reunited next summer when Keita completes his £48m move to Anfield. The pair previosuly played together in Austria with Red Bull Salzburg and speaking to 'GOAL', Keita has revealed that the Senegalese was a huge help to him in his early days in the country.
"At first, I wasn't starting and it was very frustrating," Keita explained. "I didn't like it and it made the settling-in period harder. But Sadio said: 'My little brother, stay calm. Your chance will come and when it does, you will make the most of it'.
"He helped me with everything - the language, making friends, understanding the club and the city. And, of course, he was right. Once I was put into the team, I showed my qualities and everything went much smoother.
"Salzburg improved me as a player and I learnt so much there, I got a really tactical education. Sadio was important for me, he still is! To me, he's my big brother. He really likes to learn new things, to improve and to push himself and we are the same in this way. He's a good example for me."
Mane, for his part, says that he is looking forward to playing alongside his friend once again at Anfield.
"He is a really special player and is like family to me," said Mane. "We were close at Salzburg and still keep in touch. I enjoy watching him and look forward to helping him again when he comes next year.
"He asked me about Liverpool and I told him this is an amazing club with talented players, a great manager and lots of ambition. The city and the people are really nice and he will feel at home here."