Mane netted through a close-range shot on 56 minutes and Paris Saint-Germain defender Abdou Diallo scored a similar goal nine minutes from time as Senegal beat bogey team Togo 2-0 in Thies.
Keita set up Francois Kamano, who gave Guinea a seventh-minute lead over Guinea-Bissau in neutral Nouakchott that was surrendered just after half-time when Joseph Mendes struck to earn a 1-1 draw.
Unlike Mane and Keita, who played as their countries are not on the United Kingdom Covid-19 travel 'red list', star Liverpool forward Mohamed Salah could not turn out for Egypt against Angola in Cairo.
Two-time African Footballer of the Year Salah faced 10 days' quarantine on his return from red-listed Egypt, potentially missing four matches, had he travelled.
In his absence, record seven-time African champions Egypt won 1-0 in Group F with Mohamed 'Afsha' Magdy converting a fifth-minute penalty kick.