Host Greece rallied to tie South Korea, 2-2, in Thessaloniki.
"It was an exciting crowd that helped turn the game and get one point -- which may prove a treasure," Greece's Ieroklis Stoltidis said.
After its surprise triumph at last month's European championships, the Greeks hoped for a big performance from their Olympic squad. When Loukas Vyntra's own goal in the 64th minute added to Kim Dong-jin's first-half strike for the Koreans, it didn't look good for Greece, down 2-0.
Ioannis Taralidis scored in the 78th minute and Dimitrios Papadopoulos, the only European championship player on the Olympic squad, made it 2-2 four minutes later.
"It was like I was playing football for the first time," Taralidis said. "I haven't experienced an atmosphere like that before."
* ARGENTINA 6, SERBIA AND MONTENEGRO 0: Argentina began its quest for a first Olympic gold medal in more than half a century with a demolition of Serbia and Montenegro.
Boca Juniors playmaker Carlos Tevez scored twice and new Manchester United signee Gabriel Heinze was also on target in Patras.
The South Americans have probably the strongest squad at the Olympic tournament, which is an under-23 competition with three over-age players allowed per team.
Argentina has not won an Olympic gold medal in any sport since the 1952 Helsinki Games.
* TUNISIA 1, AUSTRALIA 1: Ali Zitouni scored in the 69th minute to give Tunisia the draw in Heraklio.
Zitouni scored from close range after a pass from Mejdi Traoui, who chased down the ball to the right of the net after Australia goalkeeper Eugene Galekovic deflected a long-range shot.
The Australians scored in the final minute of the first half on John Aloisi's six-yard header.
The match was marred by 42 fouls and seven yellow cards. Tunisia outshot Australia, 9-3.
* MEXICO 0, MALI 0: In Volos, Mali held Mexico to a tie to keep alive Africa's bid for a third triumph in a row.
After Nigeria's victory at the 1996 Games and Cameroon's gold medal at Sydney four years ago, Mali -- which ousted Cameroon in qualifying -- is one of four African nations chasing the men's title in Greece. The others are Tunisia, Morocco and Ghana.
* JAPAN 1, SWEDEN 0: Eriko Arakawa rolled the ball into an empty net in the 25th minute, taking advantage of a goalkeeping blunder in upsetting the World Cup runner-up in Volos. Swedish goalkeeper Caroline Jonsson had raced Arakawa off her line but fumbled the ball on the ground and Arakawa capitalized.
* GERMANY 8, CHINA 0: In Patras, Birgit Prinz scored four goals and Germany had six second-half goals in the blowout. Prinz scored the first two goals in the 13th and 21st minutes and Pia Wunderlich made it 3-0 in the 65th. China's defense collapsed after that, allowing two more goals by Prinz and goals by Renate Lingor, Conny Pohlers and Martina Mueller.
* BRAZIL 1, AUSTRALIA 0: Marta scored in the 36th minute in Thessaloniki to give Brazil the victory.