Aguero treble after two missed penalties
S Bucharest 0 Man City 5
Sergio Aguero scored a hat-trick and missed two penalties as Manchester City all but secured a place in the Champions League group stage.
David Silva and Nolito were also on target as City, with Joe Hart again on the bench, eased to victory in the first leg of their play-off in Romania and maintained Pep Guardiola's winning start.
City's success would have been even more convincing had Aguero not missed twice from the spot in the opening 20 minutes - continuing a poor European record - but ultimately that won't matter heading into next week's second leg in Manchester.
Guardiola again left England No 1 Hart on the bench and rumours that his future may lie away from the Etihad Stadium are growing.
Yaya Toure was also left watching at home in Manchester after being omitted for a second successive game.
Still, City flew out of the blocks in impressive fashion, And, just as against Sunderland at the weekend, the revitalised Raheem Sterling won a penalty in the opening minutes, but Aguero's limp effort was saved.
Silva, though, rifled home the opener on 13 minutes after Sterling robbed Alin Tosca.
Aguero again failed from 12 yards after Aleksandar Kolarov was impeded, blasting over. It was his fourth penalty miss from his last five in European competition.
But despite this shortcoming, City looked irresistible at times with Sterling, Silva and Kevin De Bruyne buzzing menacingly.
Aguero finally got on the scoresheet four minutes before the interval, clinically firing home from a Sterling cross.
Nolito got his first City goal from De Bruyne's clever pass, and Aguero added two late goals to complete the rout.