CARDIFF, Wales — Japan upset Spain 1-0 on the first day of the men's Olympic football tournament on Thursday, 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 Friday'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.