Zenit fans held up a banner insisting they will 'die' for the club amid the coronavirus crisis.
Their supporters were watching their side thrash FC Ural 7-1 on Saturday in front of a packed stadium despite many countries suspending mass events.
The banner in the crowd read: 'We are all infected with football and will die for Zenit.'
Arriving fans had their temperature screened by sanitary workers, who wore face masks amid the coronavirus crisis.
Russia have so far confirmed more than 50 cases of the novel coronavirus (Covid-19), with 5 cases in St Petersburg.
Despite the pandemic gripping the globe and causing chaos to the sporting calendar, Zenit's match went ahead with thousands turning out to watch their side claim a big victory.
Sadar Azmoun's hat-trick for the hosts ensured his side moved nine points clear at the top of the Russian Premier League.
Zenit scored four after 27 minutes by which point Azmoun had scored twice along with strikes from Artem Dzyuba and Malcom.
That was Malcom's first goal since a big-money move from Barcelona in August.
Azmoun completed his hat-trick after the hour mark before Ural's only goal came from the penalty spot courtesy of Andrey Panyukov.
Sebastian Driussi and Dzyuba added the sixth and seventh goals of the day for Zenit.