United States midfielder Landon Donovan was left without an answer as to why what would have been a winning goal in their World Cup Group C match against Slovenia was disallowed.

The Americans fought back from 2-0 down to 2-2 when Donovan put a free-kick into the box and Maurice Edu applied the finish - but Malian referee Koman Coulibaly ruled it out and did not give any reason.

Donovan said: "I'm assuming it was a foul somewhere, it couldn't have been offside. We asked many times who the foul was by but he wouldn't or couldn't explain it."