Arsenal suffered their first defeat of the season on Tuesday, as Lens came from behind to win a tense Champions League battle 2-1 in France, due to a brilliant second-half strike by Elye Wahi.
Gabriel Jesus scored in the 14th minute to calm a noisy Stade Bollaert, giving the Premier League side an excellent start.
But Adrien Thomasson quickly equalised for last season’s Ligue 1 runners-up, and the visitors saw Bukayo Saka stagger 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.
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.
Jesus Strikes First
They had not mustered a shot until Saka pounced on a loose ball back towards his own goal from Thomasson. Saka fed Jesus and he finished clinically.
It was a harsh lesson for Lens on what can happen if you make the slightest mistake at this level, but they did not let their heads go down and capitalised on an Arsenal error to draw level on 25 minutes.
David Raya, again preferred to Aaron Ramsdale in goal, was out of his box when he tried to flight a pass out to the Arsenal right. The pass was intercepted and immediately sent forward to Wahi, who did brilliantly to control the ball and lay it off for Thomasson to score with a magnificent first-time strike.
Another setback followed for Arsenal as Saka went down just after the half-hour mark and was unable to carry on, with Fabio Vieira taking his place.
Both teams had chances shortly after half-time, but what had become an even contest hinged on two remarkable moments around the midway point in the second half.
First Takehiro Tomiyasu met an Arsenal corner first-time only to be denied by a stunning instinctive save from Brice Samba, and then Lens took the lead three minutes later.
Przemyslaw Frankowski curled a cross from the right flank back out towards Wahi in the middle, and the young striker swept a first-time shot low into the far corner to make it 2-1 and lift the roof off the stadium.
The home side then withstood an Arsenal assault in the final minutes, with one heroic block from Jonathan Gradit summing up their performance.