Updated

Japan pulled off the first big surprise of the men's Olympic soccer tournament Thursday, as Yuki Otsu scored in a 1-0 win over 10-man Spain at Hampden Park.

Otsu met a Takahiro Ohgihara corner kick at the far post in the 34th minute to slip a shot past Spain goalkeeper David De Gea, as Japan took control of Group D after the opening matches.

Japan is first in the group on three points. Spain, which includes players off its Euro 2012 championship team, is last in the group. The men's tournament is contested by Under-23 teams, with three overage players allowed per country.

"It was an important win for us. Spain are a very strong team in the group and we played well against them," Japan defender Maya Yoshida said. "We worked really hard and we will enjoy our victory. We can get a lot of confidence from this."

Juan Mata, a senior Spanish international, forced a save from Japan goalkeeper Shuichi Gonda in the 25th minute, but the game turned in the favor of Japan in the closing minutes of the first half.

Otsu ran onto the corner, which cleared a host of players on the near side, to deposit the lone goal. A few minutes later, Inigo Martinez was sent off to put Spain down a man for the remainder of the match.

Japan was more dangerous with the man advantage and had numerous opportunities to put the game away but failed to add to its lead. Spain was not able to take advantage, and one of the favorites now faces an uphill battle.

"(Japan is) a good team as well and they played as a group and they deserved to win," Mata said. "We need to improve some things (in out next two matches) and we have to play better."

Also in Group D, Jerry Bengtson scored twice in a 9-minute span of the second half as Honduras tied 10-man Morocco, 2-2, at Hampden Park in the opening game of the men's tournament.

Abdelaziz Barrada staked Morocco to the lead on a beautiful side volley in the 39th minute but Bengtson responded with goals in the 56th and 65th, the latter on a penalty kick.

Zakaria Labyad notched the equalizer for Morocco in the 67th, and the African nation held on for a draw despite the sending off of Zakarya Bergdich with 20 minutes remaining.

In Group B, Giovani dos Santos and Raul Jimenez missed late chances and Mexico settled for a 0-0 draw against South Korea in Newcastle, England at St James' Park.

"We're pretty happy with the draw. Even until the end we were attacking and trying hard to score," Mexico coach Luis Fernando Tena said. "Unfortunately the match did not end as we would have liked."

Later today, United Arab Emirates plays Uruguay, Gabon plays Switzerland, Brazil plays Egypt, Belarus plays New Zealand, and host Great Britain plays Senegal.