Zenit made it five wins from five in the Champions League this season with a 2-0 victory over Valencia at the Petrovsky Stadium on Tuesday.
Oleg Shatov's clever finish handed the Group H leaders the advantage after just 15 minutes and they rarely looked like surrendering it during a diligent display.
Valencia found it tough to maintain possession and chances were few and far between, although Santi Mina did have the ball in the net midway through the second half only to be ruled offside.
A superb team goal, finished by Artem Dzyuba, secured the victory for Andre Villas-Boas' side before Ruben Vezo was sent off for bringing down Shatov as he raced clear on goal in the closing minutes.
The result puts more pressure on Valencia coach Nuno Espirito Santo and gives Gent the chance to leapfrog the Spanish club into second when they take on Lyon.
Valencia, who handed a surprise start to 18-year-old Rafa Mir, enjoyed a strong start but Jose Gaya had to be alert to prevent Domenico Criscito's deflected cross from looping into the far corner.
And it was the Russian champions who grabbed the lead on 15 minutes when Dzyuba prodded the ball through to Shatov who, having just stayed on-side, kept his composure to chip the ball beyond Jaume Domenech and into the corner of the net from close range.
A Mir effort was blocked at the near post by the covering Luis Neto as Valencia began to push for an equaliser, but Axel Witsel spurned a glorious chance to double the lead when he failed to connect properly with Danny's header across goal, although the offside flag was raised to spare his blushes.
Paco Alcacer was kept quiet throughout most of the first half but he headed Sofiane Feghouli's cross wide before snatching horribly at another opening after good work from Andre Gomes just before the break.
Valencia were struggling to find a way through a supremely well-organised Zenit defence, while Hulk's forward runs and dead-ball deliveries proved a constant concern, with Domenech having to react smartly to stop one corner curling into the roof of the net.
Substitute Mina finally found space in behind the back four and slotted well beneath Yury Lodygin, but he was correctly flagged offside after just straying beyond the last man as Gomes slid the ball through.
A Gomes free-kick bobbled dangerously through the six-yard box and the 22-year-old rasped a shot from 30 yards off target, but Nuno's men continued to labour in the attacking third and, on 74 minutes, Zenit produced a superb team goal to seal the win.
Danny found Shatov, who clipped an excellent first-time return pass through the defence and into the Zenit captain's path, allowing him to square selflessly across goal and give Dzyuba a simple tap-in from six yards.
Valencia poured men forward and were left exposed on a subsequent break, and Ruben Vezo was issued a straight red card after his lunging tackle brought down Shatov on the edge of the area with 10 minutes to play, compounding a miserable night in St Petersburg for the visitors.