We can turn CL tie around - Wenger
Arsene Wenger was not impressed by the manner of Arsenal's 2-1 Champions League loss in Porto, but maintains the tie is still very much alive.
The Gunners have it all to do to reach the quarter-finals after blunders from goalkeeper Lukasz Fabianski proved costly at Estadio do Dragao.
The Poland international, deputising for the injured Manuel Almunia, was caught out of position to gift Porto an early lead.
Veteran Sol Campbell equalised with his first Arsenal goal since the 2006 Champions League final, only to then be involved in the match's controversial moment at the start of the second half.
Fabianski picked up what was deemed a back-pass from the former Gunners captain, with referee Martin Hansson - the Swede who missed Thierry Henry's infamous handball in France's World Cup play-off against the Republic of Ireland - allowing it to be taken quickly as Falcao swept the ball into the net.
Wenger was far from happy with the whole incident.
"It is difficult to swallow a defeat like that," said the Arsenal manager.
"The goals we conceded were difficult to imagine in a Champions League game."
Wenger, though, insisted: "We are still in the tie and have a good opportunity to turn it around in the second game.
"I am convinced we will do it."
The Frenchman could, however, not fathom why the second Porto goal was allowed to stand.
"The back-pass was accidental. The ball hit Sol. It was not on purpose and it has to be intentional to be a free-kick.
"It is difficult to understand how the referee can interpret that.
"Then, on an indirect free-kick, if you allow the team to play quickly, just five metres from the goal, how can you defend that?
"It is better than a penalty. It was unbelievable that he allowed Porto to play straight away and push the ball into the net.
"I have never seen that and I have been in the game a long time.
"It is difficult to understand. It is completely inappropriate that he allows that in such a situation.
"When the referee gives the free-kick he has to allow us a chance to defend it, otherwise it is better to give a goal straight away.
"From a situation where there was no goal chance at all, and no free-kick as well, the referee gives them just a goal."
In the build-up to the game, Wenger maintained he had complete faith in Fabianski, who was less than impressive in the recent FA Cup defeat at Stoke.
The Arsenal boss said: "You have to accept you lose as a team and win as a team. Any individual performance has not to be analysed publicly."
Arsenal captain Cesc Fabregas urged his team to cut out costly errors.
"When you concede these goals you cannot go anywhere, schoolboy goals, what can you do?" Fabregas said.
"Maybe we are still a little soft in that aspect. As a team when we concede we are not strong enough to lift ourselves. We were not strong enough to stand up and play well."
Porto coach Jesualdo Ferreira, meanwhile, had few complaints about the manner of his team's victory.
He said: "It was a legal goal, one born of the intelligence of a Porto player.
"Thierry Henry also did the same thing when he played for Arsenal.
"It gives a definite advantage to Porto now in the tie."