Aaron Ramsey and Alexandre Lacazette both scored twice as Mesut Ozil put on a Europa League masterclass to overwhelm CSKA Moscow and all but book Arsenal's place in the semi-finals.
Arsene Wenger knows winning this competition is the only realistic way his side can get back into the Champions League as they sit 13 points adrift of the Premier League's top four.
He named his strongest side, with Petr Cech returning in goal, and they showed far too much for their Russian visitors with first-half braces for Ramsey and Lacazette sealing a comfortable 4-1 win ahead of the return leg.
Reported Arsenal target Aleksandr Golovin had equalised for Moscow with a stunning free-kick but Viktor Goncharenko's side were guilty of spurning several other decent chances and have it all to do in a week's time.
Despite their three-goal aggregate advantage, Wenger is not taking a semi-final spot for granted.
"We scored some great goals in the first half and at half-time the target was not to concede any more and, if possible, add another one," said the Frenchman.
"We did the first part of the job in the second half but not the second part of the job.
"On the other hand, it will help us to focus completely in the second game and not think it's job done, we know it's not over.
"We have to go there with that right focus and try to win the game."
Arsenal can be backed at 11/10 to win the return leg in Russia next week.
Europa League quarter-finals first legs
- Arsenal 4-1 CSKA Moscow
- Atletico Madrid 2-0 Sporting Lisbon
- Lazio 4-2 RB Salzburg
- RB Leipzig 1-0 Marseille