FC Porto’s Ruben Micael (right) and Arsenal’s Samir Nasri battle for possession during their Champions League match in Oporto, on Wednesday

Oporto: Two horrendous errors by Lukasz Fabianski condemned Arsenal to a 1-2 Champions League defeat away to Porto Wednesday.

Given their crippling injury list, Arsene Wenger may have settled beforehand for such a margin, which keeps alive their hopes of reaching the quarter finals.

But the manner in which the goals were conceded left the manager seething with anger and the bulk of the blame rests with his inexperienced Poland goalkeeper.

Fabianski’s mistakes overshadowed a remarkable comeback by Sol Campbell, who equalised on his first Champions League appearance for Arsenal since the 2006 final, the stage for his last goal for the club.

The former England defender was involved in the mix-up that led to Porto’s winner, Fabianski picking up a back-pass from Campbell that allowed Falcao to score from a quickly taken free kick.

Wenger remonstrated furiously with Martin Hansson, the Swedish referee at the centre of the “Hand of Henry” controversy surrounding France’s World Cup play-off elimination of Ireland, for allowing the goal.

“The referee should give the defending team time to build a wall,” Wenger said. “If you do not let a team build a wall then you can never defend a free kick like that. There was a penalty for us as well, I do not understand those decisions.”

Cesc Fabregas, the Arsenal captain, was less willing to blame the officials. “I have no idea whether the goal should have counted — I think maybe I would have done the same thing,” he said. “You cannot go anywhere and concede goals like that. It was schoolboy football. Until the second goal we were doing OK.”

Porto’s first goal was a horror show. Fabianski was not helped by the ease with which Silvestre Varela escaped down the right in the 11th minute to beat Gael Clichy, but there is still no way he should have been beaten.

Varela’s cross from the right was nothing more than a speculative effort across the face of goal, which Fabianski got down to his left to parry, only to let the ball slide through his grasp.

If the first goal was a freak accident attributable to nerves, the second, in the 52nd minute, was down to muddled thinking. Campbell was also partly culpable for passing the ball back to him when a more sensible approach would have been to blast it into the stands, but the bulk of the blame should rest with Fabianski.

Having seen Campbell touch it back to him, he inexplicably picked it up and then compounded his error by passing the ball to Hansson after the referee had correctly awarded an indirect free kick. Porto took full advantage, Ruben Micael squaring to Falcao, who scored easily.

In Munich, Bayern snatched a last-gasp 2-1 win over defiant Fiorentina with a Miroslav Klose goal which both coaches agreed was several metres offside.

The controversy surrounded Klose’s 89th minute header overshadowed Bayern’s achievement in notching their 13th successive win in all competitions.

Fiorentina were down to 10 men and hanging on grimly when Arjen Robben’s powerful drive was parried by Fiorentina goalkeeper Sebastien Frey.

The ball fell to Ivica Olic, who headed on for Klose to score with another diving header.

Bayern went ahead with an Robben penalty in first-half stoppage time after a foul on Franck Ribery, the Dutchman sending Frey the wrong way. Per Kroldrup levelled for the Italians five minutes after the restart, turning in the ball from close range after a corner.