Felipe Caicedo scored for Lazio as the Italian side drew 1-1 at Zenit St Petersburg.
Aleksandr Erokhin gave Zenit a first-half lead in the Group F game, played in front of several thousand spectators allowed under local regulations, before substitute Caicedo levelled with eight minutes left.
Lazio, who have five points from three games, said on the eve of the match that some members of the squad had tested positive before travelling to Russia.
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They were not named but coach Simone Inzaghi said that goalkeeper Thomas Strakosha, midfielder Lucas Leiva and leading scorer Ciro Immobile were among those who stayed behind.
The first half hour was a cagey affair before Zenit, who picked up their first point, broke the deadlock. Yuri Zhirkov crossed from the left and, after a quick session of head tennis among three Zenit players, Erokhin volleyed home from close range.
Andrei Mostovoy fired wide for Zenit just after the hour before Lazio finally found some urgency. Joaquin Correa sounded a warning when he shot narrowly wide before Caicedo swept home Sergej Milinkovic-Savic's pass in the 82nd minute.
The well-travelled Ecuadorean has made a habit of coming off the bench and scoring late goals, most recently in the 4-3 win at Torino on Sunday when he grabbed the winner in the eighth minute of stoppage time.
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