Both countries subdued their semifinal opposition Tuesday with a barrage of goals. Argentina blasted archrival Brazil, 3-0, as Sergio Aguero awakened from his indifferent form to score twice, and the Nigerians rolled out their own two-goal hero in Chinedu Ogbukem Obasi as they overran Belgium, 4-1.
Brazil had yet to concede a goal in Olympic play when it took the field against Argentina in the Beijing Workers' Stadium yet spent most of the first half defending as Lionel Messi and his teammates took the initiative. Aguero fired wide with a quickly taken free kick that surprised Brazil, and late in the half Messi buzzed free to test keeper Renan with a sharp drive.
Right back Rafinha tried to inspire Brazil by raiding up the right flank, but with Ronaldinho sadly out of touch and striker Rafael Sobis starved of support, Brazil's possessions usually petered out in midfield. A few of the tackles were late and heavy and three players received cautions.
Argentina broke through in the 52nd minute with a goal somewhat controversial, as so many have been in this long and bitter rivalry. Gago played a ball to Angel Di Maria on the left flank, and Di Maria hammered a ball across the goalmouth that Aguero turned his body to meet and steered into the net by letting it carom off his arm and chest. The Brazilians appealed for handball but referee Martin Vazquez, an Uruguayan by the way, let the goal stand.
Argentina pressed forward as Brazil tried to regroup and scored again six minutes later, again with service from the left side. This time, Ezequiel Garay hit the ball low and Aguero met the ball at just the right angle to direct it past Renan.
Brazil picked up its pace and made a game of it, at least for a brief period, and were denied twice in quick succession as they battled to cut the lead in half. Sobis banged a shot off the post shortly after Aguero's second goal, and in the 65th minute Ronaldinho rattled the crossbar with a fierce free kick and Alexandre Pato pounced to tap the rebound into the net, only to see the assistant referee with his flag raised for offside.
The Brazilians couldn't contain their rivals, however, and when Messi slipped a pass to Aguero in the penalty area with a hat trick in his sights, Breno chopped him down. Captain Juan Roman Riquelme stepped up to bury his kick along with the Brazilian hopes.
Brazil finished the match with nine men, Lucas and Thiago Neves drawing red cards for harsh fouls on Javier Mascherano, whose knifing tackles and incessant chatter had antagonized many a Brazilian during a frustrating night that once again denied them a chance to capture the only major soccer honor their nation has yet to win.
Belgian keeper Logan Bailly, injured and replaced in Belgium's quarterfinal upset of Italy, regained his place in time to face a Nigerian juggernaut.
Right from the start, Nigeria's pace and power forced Belgium into desperation tackles and frantic clearances.
Bailly rescued his team twice in the opening minute, palming away a cross from Peter Odemwingie and then saving a shot by Sani Kaita when his teammates couldn't clear the rebound. Kevin Mirallas, one of Belgium's scorers against Italy, fluffed a chance when Nigeria couldn't clear a bouncing ball, and soon thereafter Nigeria broke the deadlock.
Bailly saved again from Ogbuke Obasi in the 17th minute but from the ensuing corner Femi Ajilore drilled a shot that was blocked and Olubayo Adefemi rammed it into the net from 18 yards out.
Nigerian defensive lapses have been documented and discussed during this competition and they nearly gave the goal back right away, but after Anthony Van den Borre played a clever ball to Tom De Mul, they managed to deny De Mul at the decisive moment.
Solomon Okoronkwo and Odemwingie shot wide from good positions in the late stages of the first half to keep the scoreline at 1-0 at halftime, after which the Belgians twice forced Nigerian goalie Ambruse Vanzekin to deny them equalizers. He stopped Mirallas with an excellent save that produced a corner kick that De Mul directed to Jan Vertonghen, whose first-time shot Vanzekin smothered.
That was all for Belgium. Substitute Victor Anichebe set up Ogbuke Obasi for his first goal in the 59th minute and despite him missing a great chance a few minutes later, when provided with yet another opportunity as the Nigerians ran rampant Ogbuke Obasi uncorked an unstoppable missile from the edge of the penalty area.
Chibuzor Okonkwo added a fourth goal in the 78th minute and Crew midfielder Emmanuel Ekpo would have tacked on a fifth if not for Bailly's flying save. Laurent Ciman drove home a free-kick in the 89th minute to give Belgium a goal it deserved just for getting this far, and doing what it could to stem a most relentless Nigerian wave.