A Pierre-Emerick Aubameyang header with three minutes remaining was enough to swing the tie in favour of Arsenal, who had been heading out on away goals before their skipper nodded in a Bukayo Saka cross to make it 3-2 on the night.
That was enough to see Mikel Arteta’s side advance into the last 16 despite making life hard for themselves in Athens.
This was Arsenal’s ‘home’ leg but due to current coronavirus travel restrictions it was played 2,000 miles away at the Gerogios Karaiskakis Stadium.
Arsenal went a goal ahead through Aubameyang only for Diogo Goncalves to level with a fine free-kick and Rafa Silva to put Benfica ahead following an error from Dani Ceballos.
Arsenal needed to score twice to progress into the next round and pulled one back through a low Tierney strike before Saka stood up a cross to the back post, where Aubameyang was on hand to head in a dramatic 87th-minute winner.
“We all make mistakes all the time,” Tierney said after the win. “Sometimes they get punished and sometimes they don’t but in European competition they are going to (get punished) and they did.
“We bounced back the best way we possibly could and I think it is a good step for us to show we can face adversity, come back and go through.
“We never seem to do it the easy way. But credit to the boys we had some tough moments out there and some setbacks but to bounce back, score and go through to the next round is all that matters.”
Tierney refused to be drawn on how far he believes Arsenal can go in this season’s competition - which presents them with their best chance of qualifying for European football next year.
“We are taking it game by game,” he added. “We are not looking too far ahead, we have a big game on Sunday as well, the games are coming fast right now so we can only look at one game at at time.
“I’m happy - I wouldn’t have cared who scored, I just wanted to get the goals as quickly as we could and Aubameyang, as he always does in the big moments, produced.”
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