Manchester United and Manchester City's Champions League football aspirations will go down to the wire after both English Premier League giants suffered wobbles in Tuesday's group action.
Benfica reached the Champions League knockout stages for the first time since 2005 when it held a sloppy Manchester United side to a 2-2 draw at Old Trafford.
The English champion and last season's runner-up paid a heavy price for defensive blunders and needs a draw in its final Group C match at Basel to advance. Basel, which hosts Sir Alex Ferguson's three-time winner in the final match, is only a point behind after edging out Romania's Otelul Galati 3-2.
City, for its part, slides to a 2-1 loss to Napoli — which had already held it in Manchester — with Edinson Cavani twice on target, leaving coach Roberto Mancini frustrated.
“I don't think we deserved to lose this game (but) we conceded two stupid goals,” said Mancini. But he added “I don't think it's finished.”
It will be, however, if Napoli polishes off still pointless Villarreal of Spain in its final encounter.
With Bayern Munich dispatching Villarreal 3-1 in Bavaria — Franck Ribery twice on target — the Germans win Group A but City has now slipped to third a point adrift of Napoli after the Italians showed true grit to bag a precious win, helped by Cavani's predatory powers.
Napoli went in front on 17 minutes at a jam-packed Stadio San Paolo — where Mancini then a player lost a 1990 World Cup semifinal as Argentina beat Italy — when Aleksandar Kolarov, tangling with Cavani, deflected in a Marek Hamsik corner.
Walter Mazzarri's men were unable to maintain their advantage, however, and City was back on terms after 33 minutes, Mario Balotelli tapping in a rebound after Edin Dzeko had fed David Silva, whose initial shot home keeper Morgan de Sanctis beat out.
Napoli came out fighting for the second period and within three minutes it had its nose in front for a second time.
Andrea Dossena crossed from the left and Cavani showed great poise to adjust his footing and fire past Joe Hart.
Although United's stalemate with Benfica left it both level on nine points, the Portuguese team will progress as winner of Group C if it beats Romanian side Otelul Galati in its final group game in Lisbon next month by virtue of its better head-to-head record with United.
Benfica qualifies
Benfica has qualified for the group stage regardless of what happens in the final matches — leaving United manager Sir Alex Ferguson in a reflective mood.
Inter Milan on top
Inter Milan, champion in 2010, guaranteed top spot in Group B after drawing 1-1 at Trabzonspor leaving it four points clear of its Turkish rival.
Nine-time champion Real Madrid continued its steamrollering of Group D rival Dinamo Zagreb, scoring four times in the opening 20 minutes on the way to a comprehensive 6-2 victory.
The results:
Group A: At Naples: Napoli 2 (Cavani 17, 49) bt Manchester City 1 (Balotelli 33). At Munich: Bayern Munich 3 (Ribery 3, 69, Gomez 23) bt Villarreal 1 (de Guzman 50).
Group B: At Trabzon: Trabzonspor 1 (Altintop 23) drew with Inter Milan 1 (Alvarez 18). At Moscow: CSKA Moscow 0 lost to Lille 2 (Berezutsky 49-og, Sow 64).
Group C: At Galati: Otelul Galati 2 (Giurgiu 75, Antal 81) lost to Basel 3 (F. Frei 10, A. Frei 14, Streller 37). At Manchester: Manchester United 2 (Berbatov 30, Fletcher 59) drew with Benfica 2 (Jones 3-o.g, Aimar 60).
Group D: At Madrid: Real Madrid 6 (Benzema 2, 66, Jose Callejon 6, 49, Higuain 9, Ozil 20) bt Dinamo Zagreb 2 (Beciraj 81, Tomecak 90). At Lyon: Lyon 0 drew with Ajax 0.