LONDON - Porto punished two goalkeeping blunders to beat Arsenal 2-1 and Bayern Munich's late winning goal against 10-man Fiorentina was clearly offside on a dramatic night in the Champions League.
Backup Arsenal goalkeeper Lukasz Fabianski fumbled a cross from Silvestre Varela into his own net to concede the openinggoal and then handled a backpass by teammate Sol Campbell to hand Porto its second goal.
Although Campbell's header had made it 1-1 for his first Champions League goal since the 2006 final, the second strike by Falcao - from a quickly taken free kick after Fabianski's error - gave two-time European champion Porto a first-leg victory to take to London.
Bayern made it 13 victories in a row in all competitions by beating Fiorentina 2-1 in Munich.
Arjen Robben fired the German side into a halftime lead with a penalty in the third minute of first-half stoppage time, the Dutch winger scoring for the sixth game in a row.
Per Kroldrup, who had given away the penalty for a foul on Franck Ribery, replied for Fiorentina early in the second half but Miroslav Klose headed the winner in the 89th minute from an offside position.
The Italian side by that time had been reduced to 10 men, midfielder Massimo Gobbi sent off by referee Tom Henning Ovebro in the 73rd minute for a bodycheck on Robben.
Manchester United came from behind to win 3-2 at AC Milan and Lyon beat nine-time European champion Real Madrid 1-0 in yesterday's first-leg games.
The remaining four first-leg matches are next week - Olympiakos hosts Bordeaux and defending champion Barcelona goes to Stuttgart. Inter Milan coach Jose Mourinho faces Chelsea, the club he guided to two Premier League titles in a row, and CSKA Moscow hosts Sevilla.
