Galeno curled in a sublime stoppage-time strike as FC Porto defeated Arsenal 1-0 in the first leg of their Champions League last-16 tie in Portugal on Wednesday.

Appearing in a first knockout match in Europe's premier club competition for seven years, Arsenal struggled to break down an organised Porto defence before Galeno's last-gasp stroke of brilliance.

The defeat ended Arsenal's eight-game unbeaten run against Portuguese opposition and leaves Mikel Arteta's side with plenty of work to do in the return leg in London next month.

Arteta stuck with the same starting line-up for the third game in succession following his team's 5-0 demolition of Burnley at the weekend.

Porto defender Pepe, who turns 41 next week and is the oldest outfield player in Champions League history, made his 119th appearance in the competition.

By comparison, Arsenal's starters had combined for a total of 104 before kick-off at the Estadio do Dragao.

While short on Champions League experience, Arteta has said his squad have the belief they can mix it with Europe's best.

The Gunners have started the new year with five successive wins in the Premier League, scoring 21 goals in those games, and are firmly in the race for a first title since 2004.

As well as reigning supreme in England for the first time in 20 years, the north Londoners are convinced they can also conquer Europe, spurred on further by the prospect of a Wembley final.

Arsenal have never won the Champions League -- losing their only final appearance against Barcelona in 2006.

Porto, European champions in 1987 and 2004, are a disappointing third in Portugal this term, but frustrated Arsenal throughout.

They were happy to cede possession and allow Arsenal to dictate the tempo in the first half, but it was the hosts who created the best chance.

Francisco Conceicao darted in from the right and slid over a cross that looped off a sliding Gabriel, with Galeno rifling against the far post and then steering the rebound wide after the ball came right back to him.

William Saliba and Kai Havertz headed wide at corners either side of a Nico Gonzalez drive that sailed over in a physical opening 45 minutes.

Leandro Trossard, deployed again as the leader of the attack alongside Bukayo Saka and Gabriel Martinelli, lashed over on the volley from Declan Rice's driven corner early in the second half.

Arteta made his first change with a quarter of an hour left, replacing Trossard with Jorginho, as Arsenal sought additional control in the closing minutes only to be undone by a moment of magic from Galeno.