Zambia threw out the form book on the opening day of the African Cup of Nations by handing Group A favourites Senegal a surprise 2-1 defeat.
Goals from Emmanuel Mayuka and Rainford Kalaba ensured a sensational start to the finals after success earlier on Saturday for co-hosts Equatorial Guinea on their tournament debut.
Swift counter attacks combined with sloppy defending allowed Zambia to burst into an early lead and they weathered a second half fight back to complete the upset.
"It's fantastic to beat Senegal," Harve Renard, the Zambia coach, said. "This is not a surprise, it's the result of a lot of hard work. "But there are still two games to play. We have to keep our feet on the ground and not get carried away as when you beat Senegal you think you can beat anybody."
Mayuka headed the opener after 12 minutes followed by a breakaway goal for Kalaba nine minutes later.
Mayuka's goal showed up vulnerabilities in Senegal's imposing backline with the diminutive Zambia players outjumping and outmuscling their bigger opponents for the ball.
Senegal were also caught for pace. Zambia captain Chris Katongo threaded the ball through for Kalaba to beat the offside trap for the second goal as Senegal's defence looked static.
The stunned Lions of Teranga might have given away a third goal five minutes before half-time were it not for a fine save by their American-based goalkeeper Bouna Coundoul.
But with two changes for the start of the second half, Senegal took the initiative and saw Moussa Sow and Demba Ba miss from close range before Ba again hit the bar with a header.
Substitute Dame Ndoye scored with just over 15 minutes to go by chesting the ball down and turning it home from an acute angle, but in the end his effort was only a consolation.
Senegal's impressive form in the qualifiers had left them highly fancied to dominate the group and challenge for the title but they must now beat Equatorial Guinea in Bata on Wednesday to stay alive.
Equatorial Guinea upset Libya 1-0 in the opening Group A match in Bata.
Javier Balboa struck the only goal of the game with four minutes to go.
"We played a good match," Gilson Paulao, Equatorial Guinea's Brazilian coach, said. "We had not trained a lot together but nevertheless we still won.
"The team made the most of the tactics. But despite the win, we were still short in some areas and we have to work on that."