Arsenal secured top spot in Group C and a place in the knockout stages of the Champions League with a nervy draw against Portuguese champions Porto.
Lehmann celebrates his side's progress in the Champions League
The home side, who also ensured their progress, were the better team and twice hit the post through the impressive Ricardo Quaresma.
Paulo Assuncao also saw a fine 25-yard strike go narrowly wide.
Arsenal failed to create a clear chance with Matthieu Flamini's deflected effort being the closest they came.
Gunners boss Arsene Wenger had promised his side would look to win the game and not settle for the solitary point needed to ensure progress from the group stages.
But a cautious line-up and an edgy opening suggested otherwise.
Arsenal were happy to surrender possession for long periods, showing a lack of ambition which invited Porto to attack.
But while Porto probed away, they struggled to create much in the final third.
Wingers Quaresma and Lisandro Lopez were the home side's main threat but Porto were often forced to hit speculative long-range efforts.
One such strike saw Assuncao almost break the deadlock with a wicked 25-yard strike that bent away from Jens Lehmann and went inches past the post.
Wenger was looking a frustrated figure on the touchline as his side struggled to get out of their own half.
The impressive Quaresma twice hit the post for the hosts
Arsenal finally posed a threat 10 minutes before the break when Flamini saw his shot deflected wide after exchanging passes with Cesc Fabregas.
Porto took control at the beginning of the second half and could have been out of sight within 15 minutes.
Lopez wriggled to the byeline and pulled the ball back to the impressive Quaresma whose first time shot cannoned back off the post.
Lopez then miskicked when free 12 yards out and Quaresma was left wondering what he had to do to score after seeing another fine effort beat Lehmann but come back off the German's right-hand upright.
Both sides seemed to settle for the point they needed after that brief flurry of activity and the game petered out in the final 30 minutes.
FC Porto: Helton, Bosingwa, Pepe, Bruno Alves, Fucile, Gonzalez, Paulo Assuncao, Raul Meireles (Ibson 85), Lopez, Quaresma, Postiga (Bruno Moraes 80).
Subs Not Used: Vitor Baia, Ricardo Costa, Sektioui, Vieirinha, Joao Paulo.
Arsenal: Lehmann, Eboue, Toure, Djourou, Clichy, Hleb, Silva, Flamini, Ljungberg, Fabregas, Adebayor (Van Persie 79).
Subs Not Used: Almunia, Senderos, Julio Baptista, Aliadiere, Hoyte, Walcott.
Ref: Markus Merk (Germany).