Adu was the difference between the two sides

Wonder boy Freddy Adu scored a late winner as the United States edged out Sierra Leone 2-1 on Sunday to move into the quarter-finals of the U-17 Fifa World Championship.

The unbeaten Americans had to work hard to win the game in Lahti, a small city north of the Finnish capital Helsinki.

Sierra Leone put the Americans under pressure early on, with captain and two-goal hero against Spain, Samuel Barlay, pulling the strings.

But Ghana-born Adu, 14, scored the winner in the 89th minute, as he took the ball behind the goalkeeper.

With four goals in two matches, Adu is living up to his billing as one of the players to watch at the tournament.

Sierra Leone had taken the lead after 32 minutes through Alimamy Sesay. But just seconds later, Guillermo Gonzalez equalised from the penalty spot.

The United States now leads Group D with six points from two games. Spain has four points, with Sierra Leone in third place with just a point. South Korea are yet to win or draw a game.

If Sierra Leone beats South Korea in their final match, Spain would need to a point against the United States on Wednesday night to qualify for the quarterfinals.

Meanwhile, African champions Cameroon are struggling to make the last eight after a 1-1 draw with Yemen.

It means Brazil, who drew 1-1 with the Cameroonians in their first match, top Group C with four points, after routing Portugal 5-0 in Tampere on Sunday.

The South Americans are clear favourites to beat Yemen on Wednesday and win the group, leaving Portugal and Cameroon in contention for the other quarter-final place.

In Group A, Mexico and Colombia have four points, Finland three, while China are pointless.