The second leg of their play-off went to a nerve-shredding penalty shootout. And like at the Africa Cup of Nations, Mane fired home the winning spot-kick. Salah went first for Egypt but skied his effort.
The match was somewhat overshadowed by lasers from the crowd being continuously pointed at players from both sides throughout, including during the shootout.
The Pharaoh's won the first leg 1-0 but that lead was wiped out within four minutes of the second leg's start as Hamdi Fathi's got Senegal level in the tie.
And like it did in the final of AFCON, the clash ended up going to penalties, which Senegal won, but only just.
Both sides made a nervous start to the shootout, with the first FOUR penalties not being scored, including from Salah and Senegal captain Kalidou Koulibaly, whose effort came back off the crossbar.
Ismaila Sarr scored the first penalty of the evening and Mane was given the chance to seal his country's place in Qatar after Edouard Mendy saved Mostafa Mohamed's penalty.
And like he did in Cameroon back in January, Mane made no mistake as he smashed home his spot-kick to spark ecstasy in Dakar.
Ghana also booked their place at the World Cup after claiming a 1-1 draw in Nigeria.
Thomas Partey opened the scoring on ten minutes but William Troost-Ekong's 22nd-minute penalty levelled the scores. The Black Stars progressed on away goals with the first leg finishing goalless.