Arsenal undone by Fabianski
Porto - Two errors from Arsenal goalkeeper Lukasz Fabianski allowed Porto to establish a 2-1 lead in the first leg of the Champions League last 16 tie here on Wednesday.
The 24-year-old Pole started in place of the injured Manuel Almunia but gifted the hosts an early lead with a soft own goal and presented them the opportunity to score their second five minutes into the second period by inexplicably picking up a back-pass.
The industrious Falcao was the beneficiary on the latter occasion, rolling the ball past a stranded Fabianski after Ruben Micael took a quick free-kick to secure a slim advantage for his side prior to the second leg on March 9.
Fabianski's nightmare performance distracted attention from an impressive return to European action by Sol Campbell.
The 35-year-old veteran marked his first appearance in continental competition since his return to the club in January by scoring the equaliser - three years and nine months since his goalscoring turn in Arsenal's defeat by Barcelona in the 2006 Champions League final.
Porto's winner sparked a furious reaction from Arsenal coach Arsene Wenger, who was also without William Gallas, Alex Song, Andrey Arshavin, Eduardo and long-term absentee Robin van Persie due to injury.
Wenger stormed to the touchline to remonstrate with Swedish referee Martin Hansson - who was in charge of his highest profile match since the infamous Thierry Henry handball in the 2010 World Cup finals play-off between France and the Republic of Ireland.
Hanson had turned down a strong penalty appeal from Arsenal midfielder Tomas Rosicky shortly before Porto's second goal.
Fabianski kept the score down with a save from Hulk but Arsenal continued to look unsettled at the back and will pray that Fabianski recovers morale in time for the Premier League visit of Sunderland on Saturday.
There was no gentle return for Campbell, who was exposed as early as the second minute, but having been sold short by a loose pass from Bacary Sagna he responded brilliantly to thwart Falcao with an outstretched right leg.
Hulk flashed a shot wide of Fabianski's right-hand post barely a minute later, while Campbell was perhaps fortunate to avoid punishment for a strong bodycheck on the advancing Hulk just inside the Arsenal box.
Disaster first struck for the visitors in the 11th minute, when Varela broke into space down the right before flinging a low cross towards goal that Fabianski, who had edged forward, weakly fumbled over his own line.
Arsenal, though, were quick to react and drew level eight minutes later, Campbell heading home from close range after Rosicky had turned a deep corner back across goal.
Porto goalkeeper Helton was twice called upon before half-time, pushing away a drive from Rosicky and then athletically touching a Nicklas Bendtner header over the bar, while Fabianski repelled Micael's long-range effort at the other end.