MONASTIR, Feb 8 - Nigeria dethroned African Nations Cup holders Cameroon when they came from a goal down to beat them 2-1 and reach the semi-finals on Sunday.

John Utaka scored the second-half winner on the breakaway after a tough quarter-final tussle between the two footballing superpowers of the continent.

He was quickest to a telling pass from Nwankwo Kanu, placing his ball just wide of the Cameroon goalkeeper and into the net off the upright.

Cameroon had opened the scoring in similar circumstances through Samuel Eto'o but their lead lasted just a matter of minutes as Nigeria's captain Jay Jay Okocha scored another of his trademark free kicks for an equaliser.

Cameroon's goal came with a quick counter-attack seconds after Everton's Joseph Yobo had gone wide with a long-range effort on the other side of the pitch.

Geremi knocked a long pass into the path of Eto'o, who breezed past central defender Isaac Okoronkwo and expertly placed the ball into the net for his first goal of the tournament.

But Nigeria were level just before the interval after being handed a soft free kick on the edge of the area following a tug on the collar of Utaka's shirt by Cameroon defender Lucien Mettomo.

Okocha's well-established reputation for free kick expertise was given further credence with a curling shot that slammed the back of the net before Cameroon goalkeeper Idriss Carlos Kameni had even moved.