Arsenal slumped to a first defeat of the season on Tuesday as French Ligue 1 clubside Lens came from behind to win a pulsating Champions League clash 2-1 in France thanks to a fine second-half strike by Elye Wahi.
Gabriel Jesus gave the Premier League side an ideal start when he opened the scoring in the 14th minute to silence a raucous Stade Bollaert.
But Adrien Thomasson soon brought last season’s Ligue 1 runners-up back on level terms and the visitors saw Bukayo Saka limp off before half-time.
Wahi, the 20-year-old striker who became Lens’ club-record signing when he joined at the start of the campaign, then fired home in the 69th minute and his side held on for a famous victory.
The result lifts them above Arsenal to the top of Champions League Group B on four points, one above Mikel Arteta’s side.
The other game in the group on Tuesday saw PSV Eindhoven and Sevilla draw 2-2 in the Netherlands.
While Arsenal are back in the Champions League after six seasons away, Lens are appearing in Europe’s elite club competition again for the first time in over 20 years.
That made their first European home game of the campaign all the more special, especially as it came against a team Lens famously beat in the Champions League back in 1998.
Arsene Wenger’s Gunners had been the clear favourites against Lens quarter of a century ago and Arteta’s team were here, as they arrived in northern France still unbeaten this season.
They underlined their status as the leading contenders in the group with a 4-0 demolition of PSV in their opening game, while Lens had taken heart from their performance in coming back to draw 1-1 away to Sevilla.
Saka was deemed fit to start for the visitors despite having limped off in the 4-0 win at Bournemouth in the Premier League at the weekend, and his presence was vital as Arsenal went ahead early on.