Tunisia and Cape Verde Islands began their African Nations Cup campaigns with a 1-1 draw in Group B.
Tunisia, the 2004 champions, went ahead when Jamelle Saihi played in Ali Maaloul on the left and his precision ball across the six-yard line was tucked away decisively by Ali Moncer.
But Tunisia's lead lasted only seven minutes as Heldon tucked away a penalty he won.
There were question marks over whether Ben Youssef's challenge was in the box and how much contact was made but referee Otogo-Castane pointed to the spot.
Tunisia had a chance to win the game right at the end but Wahbi Khazri's shot was wastefully wide.
Yannick Bolasie earned the Democratic Republic of Congo a point against Zambia as the other game in the group also finished 1-1.
The opener came after just 62 seconds when Rainford Kalaba's cross from the left, aimed at Ronald Kampamba, was only parried to the edge of the box by DR Congo keeper Robert Kidiaba.
Chisamba Lungu controlled but Given Singuluma took charge and curled a first-time finish into the bottom corner.
DR Congo were level in the 66th minute when Emmanuel Mbola gave the ball away to substitute Cedrick Mabwati, just on for Ndombe Mubele, and his cut-back was finished by Yannick Bolasie.