|Emmanuel Mayuka (C) scored one of Zambia's goals in the first-round upset [EPA]
Zambia survived a second-half Senegal onslaught to triumph 2-1 in Group A Saturday and create the first shock of the 2012 Africa Cup of Nations on the opening day.
Emmanuel Mayuka and Rainford Kalaba gave the Copper Bullets a two-goal lead within 20 minutes and all Senegal had to show for their dominance after half-time was a Dame N'Doye goal which set up a tense climax.
Senegal entered the tournament as 4/11 bookmakers' favourites to win the mini-league and now face a make-or-break midweek clash with co-hosts Equatorial Guinea, who snatched a 1-0 win over Libya earlier at Estadio De Bata.
Victory was a personal triumph for France-born coach Herve Renard, who has vowed to win the tournament and honour the 1993 Zambian national team whose plane plunged into the sea near Bata killing all 30 on board.
Senegal coach Amara Traore chose his starting line-up from an embarrassment of attacking riches and opted for captain Mamadou Niang, Demba Ba and Moussa Sow with new Newcastle United signing Papiss Demba Cisse on the bench.
Zambia went for Switzerland-based striker Mayuka, leaving James Chamanga on the sidelines, and the youngster repaid the faith of Renard just 12 minutes into the match.
A Copper Bullets' free kick was nodded across the six-yard box and Mayuka headed past Bouna Coundoul to give his side an unlikely lead over rivals rated third favourites for the title by pundits behind Ivory Coast and Ghana.
The Senegalese defence was all at sea and after a narrow escape the Teranga Lions fell further behind on 20 minutes when Christopher Katongo set Kalaba free and he ran across the goalkeeper before slotting the ball home.
Traore could not believe this was the same side that qualified at the expense of four-time champions Cameroon and reacted by sending on a fourth striker, N'Doye, at the expense of midfielder Remi Gomis with only half an hour gone.
Senegal finished the first half stronger, forcing a number of free kicks and a corner, and Ba was unlucky when his close-range shot was bravely blocked by Stoppila Sunzu.
Zambia were forced into their own half after the interval and Senegal twice came close to pulling a goal back through a Mohamed Diame header and a snap Ba shot as the midway point approached.
Traore brought on Issiah Dia during the break and made his final substitution on 67 minutes, replacing Sow with Cisse, before Ba saw a header come back off the crossbar.
The relentless Senegalese pressure finally told when N'Doye controlled a deep cross with his chest and then rifled a low shot past Kennedy Mweene at his near post.