Asamoah Gyan scored an extra time goal to nail Ghana's 2-1 victory over the United States in the World Cup second round on Saturday.

Gyan, who had converted Ghana's two group stage penalty shots, won an aerial challenge with Ashley Cole and kept his balance to blast home three minutes into extra time.

For the rest of extra time, the United States pressed hard and created numerous chances, which were either ruined by Ghana keeper Richard Kingson or the Americans' inabitity to finish the attack.

The Black Star controlled the first half and the speedy Americans held an upper hand in the second.

Kevin-Prince Boateng put Ghana ahead in the fifth minute and Landon Donovan pulled the Americans back on the same footing with a second-half penalty kick.

U.S. midfielder Ricardo Clark lost the possession on the halfway line and Kevin-Prince Boateng took the loose ball and stormed down the middle, jinking from two defenders to get to the edge of the box, where he struck a low left-foot shot into the bottom corner.

The fully-stretched Tim Howard could have blocked it if his right hand were half meter longer.

The American could have leveled on 34 minutes when Robbie Findley was beautifully played in down by Clint Dempsey, but Findley didn't get enough strike on the ball from 15 meters and Kingson blocked it with his left leg.

The Ghana replied with an even bigger threat as Kwadwo Asamoah, who raced down to shake off two defenders, forced a superb save from Howard.

One minute into the second half, the Americans squandered a wonderful chance as Jozy Altidore hesitated in the area and had to pass to Benny Felihaber, who hit the ball into the arms of an onrushing Kingson.

Another chance came about 10 minutes later when Landon Donovan curled in a perfect cross from the left and it beat two Ghana defenders, with the ball narrowly evading Clint Dempsey at the post.

U.S. equalized at the 63rd minute on Donovan's spot kick, which was awarded after Clint Dempsey was brought down by Jonathan Mensah in the penalty area after breaking through Ghana's defense.

Donovan smashed the penalty shot on the inside of the post to deflect into the net.

At the 75th minute, unmarked Michael Bradley raced through between two defenders into the area to smash the ball at goal, which was saved by well-positioned Kingson.

Five minutes later, Jozy Altidore stormed into the area and fell down while muscling with Anthony Annan. Before hitting the ground, the American forward delivered a shot which went half meter wide of the post.