The prolific Robin van Persie rose to the occasion once again as two second-half goals sent Arsenal FC through to the UEFA Champions League round of 16 after a close contest with the German champions. Van Persie\'s header after the interval, following excellent work by Alex Song, and his 86th-minute tap-in sealed top spot in Group F with a game to spare. However, they were made to work hard by a Dortmund side who had clearly not come seeking a draw and were rewarded with Shinji Kagawa\'s consolation goal in added time. Dortmund\'s need for three points was greater than Arsenal\'s, and they made an enterprising start as Marcel Schmelzer and Kevin Grosskreutz drove them forward. Arsenal gradually settled but the Bundesliga side\'s willingness to harry the man in possession deprived them of time and space. The first real shot in anger did not arrive until the 27th minute, when Dortmund\'s lone striker Robert Lewandowski pounced on a bouncing ball 25 metres out and unleashed a shot that flew narrowly wide. The loss of midfielders Sven Bender and Mario Götze through injury checked the visitors\' progress, though Schmelzer had a half-chance just before the break. His fierce shot flew straight into the waiting arms of Wojciech Szcz?sny. If it was hard to see where a second-half goal would come from, Arsenal provided an answer just four minutes after the restart. Song collected the ball in a central position outside the area before breaking down the left flank, beating two Dortmund defenders and chipping the ball over for Van Persie to head beyond Roman Weidenfeller. The prolific Netherlands international almost turned provider a few minutes later but Mats Hummels intervened to prevent Gervinho letting fly with Weidenfeller at his mercy. Arsenal looked to have done enough already, but they made sure four minutes from time when defender Thomas Vermaelen nodded on a corner from the left and Van Persie, unmarked at the far post, scooped the ball in – his 12th goal in eight games for the Gunners. Kagawa reduced the arrears, set up by Lewandowski, but it came too late for Dortmund. Their last-16 hopes therefore hang by the faintest thread: they must beat Olympique de Marseille by a four-goal margin in a fortnight and hope Arsenal win at Olympiacos FC.