Mikel Arteta's side needed one point to be certain of reaching the knockout stages, but they didn't settle for that target as they demolished their overmatched French opponents on a freezing night at the Emirates Stadium.
Kai Havertz, Gabriel Jesus, Bukayo Saka and Gabriel Martinelli all netted inside the first 27 minutes. Martin Odegaard added the fifth just before the interval and Jorginho bagged his first goal for Arsenal with a late penalty to cap their biggest win this season.
With one game to spare, the Gunners are guaranteed to finish in first place as they sit four points clear of PSV Eindhoven. PSV clinched the second qualification place from the group thanks to Lens' loss and their win at Sevilla earlier on Wednesday.
Securing pole position in the group means Arsenal will have the advantage of a home tie in the last 16 second leg. Arteta admitted this week that he still has something to prove in Europe as he tackles his first Champions League campaign as a manager.
The Spaniard has guided Arsenal back to the Champions League after a seven-year absence, but the closest he has come to European silverware was the 2021 Europa League semi-finals.
This was a significant statement of intent from Arteta, whose team have won four of their five group games and look capable of challenging for the club's maiden Champions League crown. With Arsenal also sitting top of the Premier League, it is shaping up to be a thrilling season for the north Londoners.
It was a miserable night for eliminated Lens, whose fans appeared to throw a flare into an Arsenal section of the stadium, while another flare and missiles were launched onto the pitch towards the Gunners players.
Lens had inflicted Arsenal's only group stage defeat in October, but
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