Francesco Acerbi's stoppage-time strike was ruled out by the Video Assistant Referee as Lazio were denied a draw at Atalanta.
Duvan Zapata's first-minute goal proved decisive as Acerbi's effort in the first minute of stoppage time was annulled in the hosts' 1-0 win on Monday night.
The result ended Lazio's five-match unbeaten run, as Atalanta moved to sixth place in Serie A, within a point and a place of Lazio in a congested mid-table.
Atalanta made a dream start when Zapata struck after 57 seconds.
He fired in low to the left, punishing hapless defending from the visitors.
Atalanta had further opportunities to extend their lead, through Remo Freuler, Josip Ilicic and Zapata, before Lazio responded and Ciro Immobile forced Etrit Berisha to save.
Berisha denied Sergej Milinkovic-Savic soon afterwards.
Immobile and Milinkovic-Savic had chances early in the second half, but squandered them.
Lazio finally thought they had the reply they had been seeking when Acerbi struck and was booked for taking his shirt off in celebrations.
But VAR ruled the effort out for offside against Milinkovic-Savic.
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