Tournament debutants Guinea-Bissau stunned the hosts, Gabon, with a 90th-minute equaliser to earn a 1-1 draw in the opening game of the Africa Cup of Nations in Libreville on Saturday. Gabon were primed to celebrate a winning start to the tournament until the defender Juary Soares headed home from a free-kick as the clock ticked round to 90 minutes, earning the rank outsiders a dramatic point from their first game at a major tournament. “We are very, very happy,” the Guinea-Bissau coach, Baciro Candé, said. “Now we have the motivation to go as far as possible.”

The late bombshell from Guinea-Bissau at Libreville’s Stade de l’Amitie silenced a Gabonese home crowd that began the game with thunderous applause for the country’s controversial president, Ali Bongo Ondimba. Gabon’s star man, Pierre-Emerick Aubameyang, lifted the noise level even higher with a goal early in the second half to put the hosts on course for an opening-day victory. Soares’ goal came from a free kick by Guinea-Bissau’s own star, Zezinho. As Soares’ header sneaked into the corner of the net, he whirled away to celebrate, pursued by his exuberant team-mates, and Gabon’s fans fell silent.

Earlier, the Gabonese fans at Stade de l’Amitie had gone through the full range of emotions at the start of an African championship they were not expecting to host but were awarded after Libya withdrew. There was a sense that the central African country – a co-host as recently as 2012 – may not have wanted the tournament this time following disputed and violent elections last year in which President Bongo retained power in the face of strong opposition. That political unease undermined the buildup to the tournament, but the appearance of Bongo was greeted with rapturous cheers by the Gabonese at the stadium. They then roared the words to La Concorde, the national anthem.

The passion and excitement quickly turned to exasperation as Gabon made little headway in the first half, with Guinea-Bissau comfortably holding their own. Gabon’s struggles were epitomised when the forward Malick Evouna, completely unmarked on the edge of the box, tripped over the ball. The former Spain coach José Antonio Camacho revived his Gabon team at half time, and they began the second half in far more promising fashion. Denis Bouanga hit a curling right-foot shot that was pushed away by the Guinea-Bissau goalkeeper just before he provided the pass for Aubameyang to score the tournament’s first goal in the 52nd minute.

As he celebrated, Aubameyang cupped his hand to his ear, as if to ask the crowd why they had stopped cheering in the first half. By the end, though, most of the Gabon fans had fallen silent again, while some booed.

“It’s very difficult to win the first match in these tournaments,” Camacho said. “For the next match we have to fight tooth and nail.”

In the other game on Saturday, also in Group A, Burkina Faso struck late to earn a fortunate draw with Cameroon.