Of course Agg 1 goal is not a difficult thing for Arsenal to chase, especially in the second leg, Arsenal will play at home, but what happened in the first leg is something that is very regrettable.
Porto played extraordinary, they seemed to be able to cover Arsenal's every move and the Arsenal players were unable to develop their game.
Agree, not a big problem for Arsenal, but they have to remain alert to their current condition, when it becomes a full defensive match for Porto, it will be hell for Arsenal. I previously forgot to mention that apart from Otavio, they also have Pepe there, so Arsenal must really solve Porto's solid defensive problem. Remember that Porto only needs a draw here to advance to the next round.
And in the other match, Barcelona drew at home to Napoli, this was in line with predictions and Barcelona quite benefited from the result of this draw because it would be easier for them to look forward to the second leg which will be played at Barcelona's home ground.
Camp Nou & Barcelona 0 - 0 Napoli, that's enough, they don't have to win. But considering how the atmosphere at Camp Nou was when Barcelona played, it seems they will have to entertain their supporters a little.