Lowly Equatorial Guinea stunned Libya and Zambia upset Senegal as the African Nations Cup began with surprises as well as tear gas outside the stadium in Bata on Saturday.
Co-hosts Equatorial Guinea, whose starting line-up consisted entirely of players born abroad, beat Libya 1-0 thanks to a late strike by former Real Madrid player Javier Balboa in the first-half of a double bill.
Zambia then scored twice in the first quarter of the game on their way to a 2-1 win over Senegal, back in the tournament after astonishingly missing out in 2010.
The tournament is already without defending champions Egypt, Nigeria, Cameroon and South Africa, who all failed to qualify.
Off the field, it was a less happy day for Equatorial Guinea, sharing the tournament with Gabon, as police used tear gas against fans trying to get into the ground.
Reuters photographs showed police firing tear gas to control supporters who apparently became impatient at delays getting into the stadium. There were no reports of injuries.
There was further embarrassment when most of the crowd left after Equatorial Guinea's match, leaving Zambia and Senegal to play in a half-empty stadium.
Organisers will be hoping for less trouble on Sunday when Ivory Coast meet Sudan and Burkina Faso play Angola in the capital Malabo in Group B.
The first match kicked off seven minutes late following the opening ceremony and a speech by President Teodoro Nguema Obiang Mbasogo, which lasted several minutes with the teams lined up and ready for kicked off.
Equatorial Guinea's win over Libya was a remarkable performance for a team ranked 151st in the FIFA rankings, although their success could also ignite controversy over their naturalised players.
Their starting line-up consisted of five players born in Spain, two in Ivory Coast and one each born in Cameroon, Cape Verde, Brazil and Liberia.
Some players qualified through their parents but there are doubts over whether the naturalised players have lived in the country for five years as required by FIFA rules.
The co-hosts, whose Brazilian coach Gilson Paulo took over only three weeks ago, created more chances and won the game when Balboa burst through and side-footed a curling effort past Libya goalkeeper Samir Aboud.
There was more to come in the second match as Zambia burst into an early lead and they weathered a second half fightback to upset the odds.
Swiss-based forward Emmanuel Mayuka headed the opener after 12 minutes followed by a breakaway goal for Rainford Kalaba nine minutes later.
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.