Japan's Yuki Otsu scores past Spain's keeper David de Gea
Brazil got their Olympic campaign off to a winning start as they resisted a second-half comeback to beat Egypt 3-2.
One of the favourites for the gold medal, Spain, put in a terrible performance as they had Inigo Martinez sent off and lost 1-0 to Japan.
Craig Bellamy's first-half goal for Great Britain was not enough as they started their London 2012 campaign with a 1-1 draw against Senegal at Old Trafford.