Porto snatched a shock last-gasp 1-0 victory over Arsenal as Galeno netted a sublime effort deep in stoppage time in their Champions League last-16 tie on Wednesday.

A drab clash was deadlocked until the fifth minute of added time when Galeno curled an unstoppable effort past David Raya to send the Estadio Do Dragao crowd wild.

Arsenal, who had scored 21 goals in their last five Premier League games, were strangely subdued in attack and failed to register an effort on target throughout a cagey contest.

They defended solidly enough but may live to regret their lack of urgency as Galeno gave Porto the edge ahead of the second leg in London on March 12.

Arsenal are seeking to reach the quarter-finals for the first time since 2010 with their last seven Champions League campaigns all ending in the last 16.

Mikel Arteta's side controlled possession but apart from a couple of headers from William Saliba and Kai Havertz, both from corners, never really looked like scoring.

Porto grew in confidence after an incredible incident in the 21st minute when Galeno thumped a shot against the far post and when the ball came back to him at pace he placed the rebound agonisingly wide of the other post.

With the 40-year-old Pepe, the oldest player to appear in a Champions League knockout round game, showing his vast experience at the back, Porto comfortably dealt with Arsenal's goal threats and England forward Bukayo Saka was very quiet.

Porto occasionally threatened and had another chance shortly before the break when Evanilson drove a shot at Raya.

The second half was even less exciting than the first until Galeno seized on a loose ball and advanced before bending a sensational shot past Raya from just outside the penalty area.