Arsenal FC took a precarious route into the last 16, scoring two late goals to overcome FK Partizan after the visitors had set the hosts' nerves on edge.
In the end it was comfortable enough as Theo Walcott and Samir Nasri scored inside the last 17 minutes to make sure of second place in Group H and a knockout phase berth for the 11th successive campaign. But when Cléo cancelled out Robin van Persie's first-half penalty, Arsenal were in danger of elimination if SC Braga could improve on what was at that point a 0-0 scoreline at FC Shakhtar Donetsk.
In their first two home games the Gunners were three up against Braga inside 34 minutes and led by two at the interval against Shakhtar. Facing the team who had long been assured of finishing bottom, they might have expected to indulge in another goal spree, but they were forced to show patience as the opening 28 minutes came and went without any threat to Vladimir Stojković's goal.
Arsenal's passing lacked its usual accuracy and Partizan were encouraged to build some promising moves of their own, with Almami Moreira taking up good positions outside the hosts' penalty area and threatening to cause problems.
Only an awkward header which Marouane Chamakh dropped onto the roof of the net had roused the Arsenal faithful. Then a jabbed cross from Alex Song found the Partizan defenders struggling to plug the gaps, and as Van Persie took possession he was clipped by Marko Jovanović. The Dutchman dusted himself down before slotting in his first goal of the season.
The Belgrade club had managed only one goal in five previous UEFA Champions League games – a penalty – and Arsenal perhaps fell into the trap of thinking they had done enough. Their efforts to add a second before the break were unspectacular and soon after the restart Nasri's attempt from Denilson's cross was rash and high.
Punishment swiftly followed as Moreira created space for Cléo. Ignoring the option of a one-two, the Brazilian let fly and his shot diverted off Sébastien Squillaci before looping over Łukasz Fabiański.
Stung by the setback, Arsenal upped the pace and Stojković was forced to tip over Van Persie's free-kick. Joy for Arsenal followed as substitute Walcott seized on a poor headed clearance to smash the ball in and four minutes later Nasri added a third. Bacary Sagna was sent off late on, but Arsenal had done enough.