The Gunners set up a final date in Baku as their dynamic front pair wrapped up a 7-3 aggregate win.
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Arsenal are through to their first European final in 13 years after Pierre-Emerick Aubameyang's hat-trick settled an absorbing UEFA Europa League semi-final.
In a week of famous comebacks, Valencia at times threatened another one in a tie that never felt truly settled until Aubameyang's second of the night made it 6-3 on aggregate with 21 minutes remaining. His late hat-trick goal added gloss.
Birthday boy Kevin Gameiro twice gave the hosts hope, making it 1-0 early on and then dragging Valencia back in it just short of the hour after goals from Aubameyang and Alexandre Lacazette had turned the tide.
Aubameyang's second of the evening finally killed Valencia off, though, and before the end he had thumped in another to make it 4-2 on the night. Unai Emery's love affair with this competition goes on.
Reporter's view: Andy Brassell
They had their hiccups in this tie, and maybe it wasn't quite as comfortable as the scoreline suggests, but Arsenal got there in the end. Mainly it was thanks to their finishing, with Aubameyang and Lacazette just too hot to handle. Valencia might feel they should have made their early dominance count, both here and in London, but once given a sniff, the Gunners' front two pulled them all the way to Baku.
Man of the match: Pierre-Emerick Aubameyang
Not just man of the match but man of the tie, Aubameyang got through an enormous amount of work in both legs, scored the goal right at the end in London to give Arsenal breathing space and then hit a clinical hat-trick tonight to see off Valencia's challenge. How do you stop him?
6: Arsenal are through to their sixth major UEFA final, their first since 2006. They have won just one so far, the 1994 UEFA Cup Winners' Cup.
19: Emery has won 19 UEFA Europa League knockout ties running (finals included); he was last eliminated from the competition in the 2011/12 semi-finals with Valencia.
4: Emery is through to a fourth UEFA Europa League final having won the trophy with Sevilla in 2014, 2015 and 2016.
28: Arsenal have won 28 European ties out of 28 after winning the first leg by two goals or more.
9: Lacazette has scored nine goals in his last 11 UEFA Europa League knockout stage games.
8: Lacazette (4) and Aubameyang (4) have scored Arsenal's last eight UEFA Europa League goals.
11: Gameiro has scored 11 goals in his last 12 starts in home UEFA Europa League games, assisting one.
9: Valencia have scored the first goal of the game in each of their last nine home UEFA Europa League matches. They won the previous eight ...
Why it's Arsenal's year
They have played with fire defensively at times but the duo of Aubameyang and Lacazette are just too good, and deserving of UEFA Champions League football next year, as well as a trophy this term. Their mutual understanding, allied to Emery's application in his specialist tournament, promises to give the Gunners the edge.
Arsenal are away to Burnley as the Premier League season ends on Sunday. The Gunners are fifth and have a mathematical chance of finishing fourth, though Emery has already conceded there's "no possibility" of the required combination of Arsenal winning, Tottenham losing and an eight-goal swing in goal difference.
Valencia, also fifth, have a more realistic chance of a top-four place: they trail Getafe by three points with two to play against Alavés and Valladolid. They could also end the season with silverware, with a Copa del Rey final date against Barcelona on 25 May.