Porto 2 Arsenal 1:A controversial Radamel Falcao effort earned Porto a narrow win over Arsenal, but the London side will take heart from Sol Campbell's away goal on his return to the tournament after four years.
Wenger had warned Porto were no European novices, the Portuguese side having consistently qualified for the elite club competition they won under Jose Mourinho in 2004. They were beaten by Manchester United in last season’s quarter-final.
Porto, who lost to Chelsea in the group stages, almost got off to a dream start. Hulk, serving a domestic ban following an altercation with a steward after a match against Benfica, cut in from the left before feeding Ruben Micael whose effort was blocked by Thomas Vermaelen.
A terrible mistake from Fabianski gifted Porto the lead after 11 minutes. The goalkeeper looked anything but comfortable in the recent FA Cup defeat at Stoke, and got his angles all wrong this time as a low right-wing cross from Silvestre Varela caught him too far forwards, deflected off his diving body and rolled over the line.
Arsenal, though, soon went on the offensive, as Nicklas Bendtner’s near-post cross was cut out. The Dane’s 20-yard effort was then deflected behind for a corner, from which Arsenal drew level in the 16th minute.
Vermaelen flicked Samir Nasri’s delivery from the left over to the far post, where Tomas Rosicky nodded it back into the six-yard box and veteran Campbell powered a header into the roof of the net for his first Arsenal goal since the 2006 Champions League final.
Arsenal started the second half well, with Rosicky looking positive down the right and having a decent shout for a penalty turned down when he seemed to be tripped. However, disaster struck after 51 minutes following another blunder by Fabianski.
The goalkeeper contrived to pick up a back-pass from Campbell just inside the penalty area. With Campbell still complaining at the decision, Porto took the free-kick immediately — which Micael quickly tapped to Falcao for the Colombian to roll the ball into an empty net.
*In tonight's other tie, substitute Miroslav Klose headed an 89th minute goal to give Bayern Munich a 2-1 win over Fiorentina.
Bayern, who had won their last 12 games in a row in all competitions, went ahead with an Arjen Robben penalty in first-half stoppage time after a foul on Franck Ribery.
Per Kroldrup levelled for the Italians five minutes after the re-start, turning in the ball from close range after a corner.
Fiorentina had Massimo Gobbi sent off for an apparent elbow in Robben's face in the 73rd minute.