Junior Makiesse scored from the spot twenty minutes from time to secure Congo a priceless victory over favourites Cameroon in Group D in Agadir on Tuesday.
The Indomitable Lions coached by Cameroon legend Rigobert Song dominated possession but failed to make their dominance count despite going close on several occasions.
Cameroon's Patrick Moukoko missed from six yards out following a swift counter on the left where Thomas Bawak and Junior Awono exchanged passes to feed Moukoko who could not find the goal three minutes before half time.
Jean Gwot was also called to action in the Cameroon goal after 12 minutes when his defence failed to clear their lines giving room for Makiesse to shoot which Gwot gathered.
William Ngoundo tried his luck from a distance but Congo goalie Barel Mouko was again in position to pull a save. Moukoko glanced in a header towards the near post before the break only for Mouko to save and keep the score level.
Mouko produced another fine save to deny Moukoko in what was an individual battle between the two.
Moukoko cut from the left channel before seeing his right foot curling strike tipped over by the impressive Congolese keeper Mouko.
Congo secured victory when they won a penalty after Gwot was adjudged to have fouled Makiesse.
The diminutive forward stepped up to send the keeper the wrong way and hand his side all three points and top spot in the group.
Angola and Burkina Faso earlier played out an eventful goalless draw in the group opener.
Total Man of the Man: Prestige Mboungou (Congo)
Rigobert Song (Head Coach, Cameroon)
In my opinion, the match was of a good level. Both teams played well; unfortunately we lost. Honestly, I have no reason to criticize my team. The players gave their maximum. Such is football; sometimes you play well but in the end lose. We have a team of very good players, who are the future. You just have to rely on them. I trust them. There are still two games left. We will make some corrections to our team for the next game.
Barthelemy Ngatsono (Head Coach, Congo)
I want to congratulate Cameroon for a good performance. I saw today a good Indomitable Lions team. For us, this victory is important because it allows it gives a good start to the competition. We are now leaders of the group and it serves a good morale. But it doesn't stop there. We have to continue working. The fact of beating Cameroon does not mean that we are at the top. We want to build a team for the future and there is a lot of work to be done.