Sol Campbell enjoyed a goalscoring return to the UEFA Champions League, but Silvestre Varela and Falcao also found the target as FC Porto ended their unhappy recent home form against English clubs, leaving Arsenal FC needing a second-leg win to reach the quarter-finals.
Tentative from the off, the Gunners faced a test of nerve after falling behind in the opening stages due to a mistake by stand-in goalkeeper Łukasz Fabiański. They quickly put their disappointment behind them thanks to veteran defender Campbell, making his first appearance at this level since scoring for Arsenal in the 2006 final. But like in Paris, Arsenal were to lose 2-1 as the opportunist Falcao stroked in the winner six minutes after the restart and the Portuguese champions will look to press home their slender advantage in London on 9 March.
Arsenal have had a recent tendency for early defensive slips and an under-hit back pass from Denilson allowed Porto to pour forward. It took a superb tackle from Campbell on Falcao, followed by Thomas Vermaelen's block from Rúben Micael, to spare the visitors the worst of starts. A fierce Hulk drive that skimmed past Fabiański's post kept the pressure on the Gunners, who cracked with just 11 minutes gone as Fabiański fumbled Varela's low centre over his own goal line.
Arsène Wenger appeared unimpressed in the Arsenal dugout, but his charges responded with character. Nicklas Bendtner speared a deflected effort wide and then a moment that belonged in a script as Campbell headed in from a set piece, just as he had at the Stade de France against FC Barcelona. Cesc Fàbregas supplied the corner, Tomáš Rosický nodded the ball back across goal from Vermaelen's flick and the oldest player on the pitch altered the momentum of the tie.
Rosický came close to swinging it even more emphatically in Arsenal's favour with a whipped shot turned wide by Helton, before Rúben Micael tested Fabiański with similar results. Porto coach Jesualdo Ferreira had predicted an open match and he was being proved correct, as Bendtner became the next player to threaten with a header that Helton did well to palm over.
It was Porto who broke through after the break, though, Fabiański penalised for picking up a Campbell back pass and Falcao finishing from Rúben Micael's quickly taken free-kick. Fabiański saved Wenger's men from falling further behind with impressive stops from Hulk and Raul Meireles, yet conceding for a second time had clearly sapped their morale and they were in danger of wilting as an attacking force.
Theo Walcott was sent on to reverse that trend, Rosický making way, however it was from dead-ball situations that the Premier League outfit looked most likely to respond. Ultimately, even that route to goal proved fruitless.