Arsenal were far from their best as they fell to a late 1-0 defeat in the first leg of their Champions League last-16 tie against Porto.
The Gunners struggled to make many chances of note and were a far cry from their recent performances despite dominating possession in Lisbon.
Mikel Arteta named an unchanged team for the third match in a row, having scored 11 goals in their last two Premier League games.
The night started in difficult fashion when club-record signing Declan Rice was given a yellow card for a late tackle less than 80 seconds into the game.
Arsenal fell to a 1-0 loss in the Champions League first leg against Porto
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Rice was forced to play the rest of the game on a booking and put in an admirable display in his first Champions League knockout appearance.
Porto had the best chance in the first half, with Gelano's first shot somehow coming back off the post before his second strike went past the other upright.
The game was mostly short of clear-cut chances, with Arsenal failing to have a shot on target.
But Gelano popped up with a stunning goal in the final minute of stoppage time to steal a win for Porto, curling a long-range effort past David Raya.
GB News looks at what we learned as the visitors suffered late heartache at the Estadio do Dragao.
Three players let Gunners down
Arsenal's front three has been on fire in recent weeks, with Bukayo Saka and Leandro Trossard in particular in fine goalscoring form.
Saka has scored a brace in his last two matches, while Trossard had netted in four of his previous five games.
But the pair were unable to have the impact they would have wanted this evening.
Gabriel Martinelli was also far from his best and was given a tough night against right-back Joao Mario.
Trossard had the chance to nail down his spot as the main striker for Arteta.
But he was taken off with 16 minutes remaining as Arteta attempted to shore up in midfield by introducing Jorginho.
Gabriel Jesus will be breathing down Trossard's neck if he is fit for the second leg in three weeks' time.
Saka and Martinelli's spots are more than safe but they'll know they weren't quite at it tonight.
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Result not disastrous
The Arsenal front three struggled to make an impact against Porto
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When away goals were a thing, the home side would generally be satisfied with keeping a clean sheet.
However, that rule went years ago and Arsenal won't be too disheartened despite falling to a late loss.
They will be big favourites to turn the match around at the Emirates on March 12 and Porto will know they have a big task on their hands to keep Arteta's team at bay.
Arsenal will hope to have several other players back from injury for that game, too.
Lack of subs
Arsenal were far from their best as they suffered a late defeat in Lisbon
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Despite naming the same team for a third match in a row, Arteta only made one substitute this evening.
Trossard being replaced by Jorginho was the only change he made during the game.
Emile Smith Rowe, Eddie Nketiah and Fabio Vieira were among those to be ignored and remain on the bench.
Perhaps the players who started the match tired towards the end and that may have cost their team the result in the final stages.