pablo aimar's second-half equaliser was enough to guarantee the portuguese side's last-16 place, leaving united with work to do on matchday six.
sl benfica secured passage to the uefa champions league round of 16 after a breathless draw with manchester united fc assured them of a top-two spot in group c.
a phil jones own goal rewarded the visitors' bright start with an early lead, but last year's finalists turned the tables as dimitar berbatov and darren fletcher struck either side of half-time. yet pablo aimar's equaliser means jorge jesus' side will win the group if they beat fc oțelul galați on 7 december; united travel to fc basel 1893 needing a point to join them in the knockout stages.
benfica's fans were in fine voice at old trafford, and had even more to shout about after three minutes. the marauding maxi pereira found nicolás gaitán and when the winger cut inside, his shot was deflected into his own net by jones.
jesus' men brimmed with confidence, and the match was 17 minutes old before the home side managed an effort on goal, nani firing a free-kick straight at artur.
the visitors continued to make the running but united hit back on the half-hour. nani swung in an inviting ball from the left and berbatov's clever flicked header found the far corner of the net – the bulgarian's first uefa champions league goal since scoring twice against celtic fc in october 2008.
benfica were stunned, and united almost took immediate advantage as ashley young burst through their defence; the alert artur was out sharply and blocked well with his legs. in a thrilling end-to-end spell, benfica responded as david de gea plunged to his left to palm away an aimar shot.
united started the second period with much greater purpose than they had the first. artur kept out fabio's lofted effort, but the pressure paid off as the hour approached. fletcher ghosted in behind the defence on to patrice evra's superb floated cross, and though the valiant artur blocked well, the scottish international midfielder converted the rebound.
back came benfica; two minutes later they were level. bruno césar pounced on a poor de gea clearance and though rio ferdinand intercepted his cross, aimar was on hand to lift the ball high into the net. berbatov almost added a further late twist but fired over and united have work to do on matchday six to avoid elimination. benfica, with superior head-to-head records against united and basel, have no such concerns.