In the last minute of added time, the right-back Eric Sikora, who had earlier hit the bar from one free-kick, had another well saved by David Seaman. From the resulting corner, the home captain, Frederic Dehu, was allowed a flicked header and Tony Vairelles forced the ball in.
Arsenal had dominated during a critical period early in the second half, when Marc Overmars emerged from anonymity to score a well-taken goal.
The equaliser apart, England's double winners defended with all the experience gleamed from so many similar battles at home and abroad down the years. Emmanuel Petit and his compatriot Patrick Vieira were solid in the centre of midfield until Petit fell victim to a bad tackle. While in attack Dennis Bergkamp achieved the performance required of him in what is likely - because of his fear of flying - to be the only away game he plays in the group.
Now, with a point lost rather than gained, the next game, at Wembley against Dynamo Kiev - whom Arsene Wenger considers to be the most dangerous of the three opponents -takes on even greater importance. Although helped by Kiev's 2-1 defeat against Panathinaikos, Arsenal need to beat them and then offer the Greeks no gifts similar to last night's.
The Arsenal manager said afterwards: "I'm very disappointed with a point because I think we had so many chances to win the game. But we were strong and well organised and played well in every department. It's very frustrating and of course I was upset, but it's part of football. I just felt something could happen even in the last minute and we lost our concentration."
With two French substitutes in addition to Petit, Vieira and Nicolas Anelka and Wenger himself, Arsenal could not complain of any shortage of local knowledge. Lens, with three recent injuries to add to their two long-term ones and the loss of three important players in the summer, were much changed from the side that achieved a remarkable Championship success last season after finishing 13th the previous year. Their starting 11 included only two internationals, both with one cap each, as opposed to Arsenal's 10 but, as expected, in front of a raucous crowd of 36,000 they had a full quota of what L'Equipe, the French daily sports newspaper, had called "Le Fighting Spirit".
There were, nevertheless, enough opportunities in the second half for Arsenal to have secured all three points and put the pressure on the other Group E members.
Wenger's promise that, with the two teams utilising an aggressive 4- 3-3, "it will not be boring" was justified as both attacked whenever the opportunity arose, albeit sometimes with more speed than accuracy.
There was nevertheless one difficult save required of either goalkeeper before half-time. That came when Vairelles, the blonde-haired hero of the "Tony Boys" section of the World Cup stadium, beat Lee Dixon near the byline, forcing Seaman to parry a fierce shot.
Guillaume Warmuz in the Lens goal had to match that soon after the interval as Bergkamp was twice played dangerously into the inside right channel in a matter of minutes.
If there was one disappointment for Arsenal at that stage, it was the ineffectiveness of Overmars, the one player in the team with Champions' League experience. Having failed to make a single penetrating run down the flanks, however, he was told to move inside more and turned up by the penalty spot six minutes after the re-start to score.
Vieira and Petit worked the ball forward, Petit's low pass in to the area finding Overmars to side foot a neatly angled shot past the stranded goalkeeper.
He might have added two more, striking first the right-hand post and then the crossbar. If those efforts were unlucky, Anelka was guilty of a wretched miss five minutes from the end, which became all the more costly as Vairelles struck right at the death.
Lens (4-3-3): Warmuz; Sikora, Meride (Rool, 75), Dehu, Etchi Oben (Sankhare, 80); Debeve, Dalmat, Nyarko; Smicer, Nouma (Moreira, 69), Vairelles. Substitutes not used: Eloi, Vernier, Diop, Marichez (gk).
Arsenal (4-3-3): Seaman; Dixon, Keown, Adams, Winterburn; Parlour, Vieira, Petit (Hughes, 72); Bergkamp, Anelka, Overmars. Substitutes not used: Bould, Wreh, Grimandi, Garde, Manninger (gk).
Referee: H Krug (Germany).
n In the other match in Group E, Panathinaikos came back from 1-0 down at half-time to beat Dynamo Kiev 2-1. Sergei Rebrov opened the scoring in the 31st minute, but the Greeks, who reached the semi-finals in 1996 but failed to qualify last year, equalised in the 57th minute with a powerful header from their Norwegian midfielder, Erik Mykland, and Nikos Liberopoulos sealed the victory with another headed goal in the 69th minute.