This year's African Nations Cup threw up another upset this afternoon as Gabon took down one of the tournament favourites, Cameroon, in the first Group D game.

Hull City striker Daniel Cousin took advantage of a defensive mix-up to grab the only goal after 17 minutes. Cameroon pressured the Black Panthers for much of the match but could produce an equaliser, as Gabon secured only their second ever African Nations Cup victory.

Cameroon did all the early pressing with Landry N'Guemo going close from a tight angle before Didier Ovono had to turn Achille Emana's snap shot from the right channel on to the post and out for a corner.

It was against the run of play when Gabon snatched the lead with less than 20 minutes gone. Cameroon's defence got themselves in a mess, allowing a mis-kicked pass from Cedric Moubamba to find its way into the path of Cousin, who slipped a low shot past Carlos Kameni.

Paul Le Guen's side almost responded moments later as Alex Song surged forward. The midfielder was brought down on the edge of the area but the referee waved play on as the ball fell for Pierre Webo, who saw his low shot saved.

Geremi's long-range free-kick then seemed to have Ovono in trouble, but he awkwardly punched it away.The second half took time to come to life but Emana almost scored an explosive equaliser with a long-range half-volley out of nothing that flashed wide.

A quick free-kick just before the hour mark released Emana inside the area but as he closed on the goalkeeper he sliced his shot horribly wide.

Cameroon were struggling to get star striker Samuel Eto'o involved and his first decent shot from inside the area was deflected wide.

Emana then forced a good save from Ovono before substitute Somen Tchoyi flashed a powerful shot wide, but it was beginning to look like it might not be Cameroon's day.

Ovono made a good save to keep out Geremi's deflected free-kick in the final minute of normal time and Song then sent Cameroon's last chance over the crossbar.

Gabon almost sealed it when Pierre-Emerick Aubameyang smashed the ball against the crossbar in injury time, but Cousin's strike proved enough.