New Delhi, Dec. 24 -- The contrast could hardly be greater.

Nicolas Jackson scored twice and Senegal started its Africa Cup of Nations title bid with a comfortable 3-0 win over Botswana on Tuesday, before Nigeria opened with a nervy 2-1 victory over Tanzania.

Both teams are among the favorites for the 35th edition of the tournament, but only one lived up to its billing.

Senegal substitute Cherif Ndiaye completed his team's scoring after Botswana goalkeeper Goitseone Phoko had prevented worse for the Zebras, who lined up with five at the back and were pinned back for most of the game.

"We have to keep going like this," said Senegal coach Pape Thiaw, who nevertheless saw room for improvement. "There are no easy opening matches."

Nigeri...