By Scott Trotter It was a brutal return to the knockout stages of the Champions League for Arsenal on Wednesday night. The Gunners looked set to navigate their first leg against Porto at the Estadio Do Dragao with honours even until Galeno’s stoppage-time strike. The Brazilian forward took matters into his own hands with seconds remaining and unleashed a curling shot from 20 yards to beat David Raya and earn the win. Mikel Arteta’s side failed to record a shot on target across the 90 minutes and now must overcome a deficit to move into the quarter-finals of the competition. They will hope to n…