Argentina moves on to a South American clasico against archrival Brazil, which downed Cameroon, 2-0, in overtime. Both men's semis will be played Tuesday.
On the other hand, Belgium proved that incurring an early red card isn't necessarily the kiss of death, as it had been for the USA in its final group game against Nigeria. The Belgians went down a man and a goal in the 18th minute yet upset Italy, 3-2.
The Tuesday semifinals match Belgium with Nigeria at Shanghai Stadium (6 a.m. ET), and Brazil against. Argentina in the Workers' Stadium, Beijing (9 a.m. ET). The winners play Saturday at the National Stadium, a.k.a. the Bird's Nest, at high noon local time (midnight ET).
AFRICAN SHOWDOWN. Victor Obinna, who scored for Nigeria in a 2-1 win that eliminated the U.S., set up the first goal for Peter Odemwingie and clinched victory from the penalty spot with eight minutes to play. In between, though, Ivory Coast exposed but weren't able to exploit the same defensive glitches uncovered by the Americans.
Striker Salomon Kalou worked his way deep into the penalty area but shot wide, and a sharp free kick from Emmanuel Kone tested Nigerian keeper Ambruse Vanzekin, who saved well on this occasion and again in the 71st minute when he pushed Gervinho's powerful drive to safety.
Nigeria confirmed its semifinal spot and a possible chance to repeat its 1996 Olympic gold medal when Chinedu Ogbuke Obasi dribbled clear and Souleymane Bamba took him down. Referee Masoud Moradi whistled and Obanni converted.
DEMBELE DOUBLE. Belgium beat Italy despite playing much of the match a man short. Moussa Dembele scored twice: midway through the first half to tie the match, 1-1, after Italy's New Jersey-born striker Giuseppe Rossi had converted his second penalty kick of the tournament, and again with 11 minutes left to win it.
Thomas Vermalen's foul and subsequent red card provided Rossi with his first of two penalty kicks and also left the Belgians playing 10 against 11, yet after Dembele equalized with a header from a corner kick Kevin Mirallas's goal two minutes into first-half stoppage time gave the Belgians a 2-1 lead.
An offside flag for a Rossi infraction denied Italy a goal a goal eight minutes into the second half, and 15 minutes later he collided with Belgian keeper Logan Bailly and earned a yellow card for simulation. Bailly injured his shoulder and Yves Ma-Kalambay replaced him.
The stand-in keeper took up a spot on the goal line after Sepp De Roover fouled Paolo De Ceglie to provide Rossi another penalty kick, which he smacked home in the 74th minute. Yet despite their man advantage, the Italians couldn't contain Dembele, and a nifty one-two with substitute Anthony Vanden Borre set him up to drill home a shot from the edge of the penalty area. Italy lost its man-advantage as well when keeper Viviano was sent off for wrestling with Mirallas in a typically asinine post-goal scuffle.
Belgium rode out the remainder of regulation and five minutes of stoppage time to reach the semifinals for the first time since winning the gold medal as host (Antwerp) 88 years ago.
DUTCH DOWNED. In a match officiated by MLS veteran Jair Marrufo, the Netherlands battled bravely against Argentina yet were no match for Lionel Messi, who, like Obanni, scored the first goal and clinched victory by notching the winner. Early in the match, after being snuffed by Dutch keeper Piet Velthuizen one-v-one, he charged down an errant pass and took the ball past the keeper to score from a tight angle.
Messi, Juan Roman Riquelme, Sergio Aguero and Angel Di Maria ran freely through midfield repeatedly but couldn't double their lead and the Argentine defense couldn't hold off the Dutch. They tied up the match in the 36th minute when Javier Mascherano blocked Evander Sno's shot and Otman Bakkal reacted first to bang home the equalizer.
Few scoring chances materialized as Argentina carried the play and the Netherlands broke forward only rarely. Regulation ended and overtime began with two fatigued teams playing carefully, but soon enough the magic of Messi returned.
In the last minute of the first extra period, he glided inside and laid a perfectly weighted ball to Di Maria knifing in from the left flank, and Di Maria evaded a desperation tackle to smack a remarkable shot with the outside of his left foot just inside the far post.
BRAZIL PREVAILS. The South American clasico thus matches the 2004 gold medalist against the world's most renowned soccer nation anxious to win the one major honor that has escaped it. Brazil labored to break down Cameroon, the 2000 gold-medal winner, which lost Albert Baning to a second caution six minutes into the second half yet held on through regulation before Rafael Sobis and Marcelo scored four minutes apart in the first extra session.
Coach Dunga left Thiago Neves and Alexandre Pato on the substitutes' bench to start the match, and brought both of them on after Baning took his second caution for a foul on Lucas. Brazil preserved its perfect defensive mark - it has not conceded a goal in 390 minutes of play at the Olympics - and eventually its offensive class prevailed.
Unable to pick its way through the massed Cameroonian defense, Brazil broke through in the 101st minute when Diego won the ball in midfield and set free Rafael Sobis with a ball he chipped over keeper Amour Tignyemb. Combination play by Ronaldinho and Thiago Neves created the second goal for Marcelo to score in unconventional fashion: from close range, he reached back to clip the ball just inside the post.