Japan upset Spain 1-0 on the first day of the men's Olympic football tournament, while Brazil held on for a 3-2 victory over Egypt and host Britain had to settle for a 1-1 draw with Senegal.

Uruguay and Belarus also won as the tournament got under way with eight matches the day before today's opening ceremony. Japan pulled off the surprising win after outplaying gold-medal favorite Spain, which went a man down in the first half and couldn't fight back.

Brazil got three first-half goals but nearly squandered the lead in the second, escaping with the victory to begin its quest for its first gold in Olympic football.
Britain's debut was spoiled by a late goal conceded in the draw with Senegal.

Japan got the winner in Glasgow when forward Yui Otsu broke away from his marker during a corner in the 34th minute and the ball landed right at his feet for a simple tap-in past Manchester United goalkeeper David De Gea.

Spain was reduced to 10 men just a few minutes after the goal when center back Inigo Martinez was sent off for a foul while trying to stop a Japanese player from scoring.

"It was an important win for us," Japan captain Maya Yoshida said. "Spain are a very strong team in the group and we played well against them. We worked really hard and we will enjoy our victory. We can get a lot of confidence from this." The loss comes as a blow for Spain's under-23 team, which wants to win Olympic gold to add to the World Cup and European Championship titles held by the country's full national team.