Iliman Ndiaye netted after 27 minutes, taking advantage of a goalkeeping error to put Senegal ahead in a tense derby against their west African neighbours.
Mali were reduced to 10 men for the second half after captain Yves Bissouma was sent off for a second caution on the stroke of halftime. He was booked first for a clumsy challenge in the 25th minute and was dismissed after a needless foul on Idrissa Gana Gueye.
Mali were down to 10 men from the 26th minute of their previous clash against Tunisia and still managed to squeeze through on penalties but there was no recovery this time around against a polished Senegalese outfit.
Meanwhile, host nation Morocco booked their spot in the Africa Cup of Nations semi-finals with a 2-0 win over Cameroon on Friday night.
The game was played at a lively pace in the early stages of the first, with Morocco giving Diaz a lot of the ball down the right flank. Cameroon, meanwhile, were forced to make a change on 22 minutes as Junior Tchamadeu was unable to recover from an earlier knock and made way for Junior Dina Ebimbe.
However, it was Morocco who sealed the win with 15 minutes left on the clock when a corner made its way to an unmarked Ismael Saibari, who took a wonderful first touch before rifling the ball into the far corner for his first goal at the tournament.
