Galeno's injury-time wonder strike left Arsenal dumbfounded as Porto claimed a 1-0 win in the first leg of their Champions League last-16 showdown.

A scrappy contest rife with fouls - 36 to be exact - and wasted set-pieces was seemingly destined to end goalless, but as the seconds ticked down, Porto's wing wizard found the far corner with a sublime strike, meaning that the Primeira Liga powerhouses will take a slender lead to the Emirates in three weeks' time.

Mikel Arteta's side dominated the ball throughout the 90 minutes, but the visitors did not have a single shot on target - the first time they failed to do so in the Champions League since losing to Barcelona in March 2011 - but Porto's unbreakable defensive structure made life incredibly difficult for the hitherto free-scoring Premier League team.

The earliest exchanges could certainly be described as two teams feeling each other out, as Arsenal settled into a period of possession, but Sergio Conceicao's team were operating with a high press and sought to limit the centre-backs' time on the ball.

Porto should have drawn first blood with the game's first gilt-edged chance in the 21st minute, as Francisco Conceicao's cross was deflected into the path of Galeno, but the Brazilian struck the far post before inexplicably firing the rebound wide of the other side of David Raya's goal.

William Saliba's blushes in particular were spared by Galeno's shocking miss - the Frenchman was totally asleep as the Porto attacker crept up behind him - but he tried to make amends from a 35th-minute Bukayo Saka corner, only to head wide at the back post.

Bedlam reigned supreme in the penalty box whenever Arsenal won a corner, with jostling aplenty and several Porto shirts hitting the deck as the ball was swung in, but Conceicao's side were effectively stifling the Gunners' well-documented threat from dead ball situations.

For all of the visitors' possession, the Dragons would fashion the most promising opportunities and created another in the 40th minute, when Evanilson stole the ball from Gabriel Martinelli and combined well with attacker Pepe down the right, but his low shot from a tight angle was straight into Raya's body.

Normal service resumed in the second half, where Arsenal once again required a set-piece to have a sight of goal - Leandro Trossard volleyed over from Declan Rice's drilled corner - but referee Serdar Gozubuyuk had already blown for a foul.

Clear-cut chances remained at a premium for both teams, although with 67 minutes gone, Pepe sprinted past Kai Havertz into the box and managed to cut back for Evanilson, whose strike was deflected over the top by an alert Rice.

Fouls and stoppages were the order of the day as the clock wound down, and after Arsenal wasted another aerial opportunity from a dead-ball situation - Gabriel Magalhaes nodded over from Rice's free kick - the teams would seemingly shake hands on a goalless draw.

However, there was time for a remarkable twist to tale in the fourth additional minute, as Martinelli cheaply gave possession away, and 20 yards out from goal, Galeno was allowed to get his strike away unchallenged and curled an exquisite strike into the far corner to spark Estadio do Dragao delirium.

Before bidding to turn the tie around in North London on March 12, Arsenal have Premier League matters to attend to against Newcastle United on Saturday, while Porto are away to Gil Vicente in the Primeira Liga on Sunday. body check tags ::