Benfica were caught while trying to play out from the back and then scored an own goal as Zenit claimed a 3-1 Champions League Group G win.
Zenit took advantage of sloppy defending to beat Benfica 3-1 and move into a strong position in Champions League Group G, with four points from their opening two games.
Sergei Semak's side built on their 1-1 draw at Lyon in the opening round with a confident performance at Saint Petersburg Stadium, where they had won four of their previous five matches in Europe's top competition.
Benfica arrived with a Champions League away record of six defeats from their last seven trips and did themselves no favours when ponderous defending allowed Artem Dzyuba to steal in and score.
With their noses in front, the Russian champions shut up shop and patiently awaited a second opening, which arrived 20 minutes from time when Ruben Dias put through his own net.
Benfica's hopes of a comeback that never looked likely ended 12 minutes from time when Sardar Azmoun rolled in his second goal of this season's competition, with Raul de Tomas' late strike only a consolation.
Just as Benfica seemed to have withstood the hosts' bright start they slipped up trying to play out from the back, Magomed Ozdoev dispossessing Lubomir Fejsa after 21 minutes and teeing up Dzyuba to confidently pick his spot before side-footing past Odisseas Vlachodimos.
Zenit dominated until half-time and Azmoun started the second period with another fast break, stinging Vlachodimos' palms with a rasping angled drive.
Substitute Vyacheslav Karavaev had been on the pitch less than two minutes when he broke down the Zenit right and delivered a low cross that Dias, sliding back to try and clear Benfica's lines, bundled into his own net with his hand.
The visitors continued to leave gaps and Azmoun was only too happy to exploit them, pouncing on Ozdoev's long pass and rounding Vlachodimos before tapping in from close range.
Yordan Osorio gifted Benfica a consolation when his clearance fell to the feet of Raul, who launched a shot into the top corner of the net, but it was too little, too late for Bruno Lage's men.
What does it mean? Benfica rock bottom
The Portuguese champions have kept seven clean sheets in all competitions this season but in Europe their defence has been poor, conceding five goals in two games to leave Benfica bottom of Group G with no points.
Industrious Driussi makes the difference
The free radical in Zenit's midfield and a constant source of creativity, Sebastian Driussi exploited the space in front of Benfica's defence and kept the hosts on the offensive.
Fejsa's fumble proves costly
Benfica looked in good shape until Fejsa hesitated in possession on the edge of his own box and paid the price.
Benfica have three weeks without a game before they entertain Lyon in their third Group G match, while Zenit face Ural and Rostov in domestic fixtures before their Champions League trip to RB Leipzig.