Mane was consoled by team-mates as he walked off the pitch in tears after helping Senegal beat Equitorial Guinea.
The Liverpool star completed the entire 90 minutes of his side’s Africa Cup of Nations qualifier win and, on seeing the images, many feared he had injured himself.
However, Senegalese media calmed these concerns, with Metro Dakar suggesting Mane's reaction was based on his performance.
Mane, who sustained a thumb injury during the international break last month, missed a chance in the second-half which was met by boos from supporters.
In an Instagram post, translated, his brother wrote: "It is rare to see a country dislike a star of his country like you do.
"All of Egypt back Salah whether or not he is playing well for the national team.
"Thousands of Egypt fans will support Salah, while Senegal fans will never support Kalidou Koulibaly or Sadio Mane, who is competing with Salah for the Golden Ball.
"He will continue to fight for you, continue to sacrifice himself and continue to give the maximum for Senegal and love and respect the national flag.
"One day you will realise, but it might be too late."
He then adds that his brother cried because; "he wanted so much more".