Ederson and Nicola Zalewski scored as Atalanta beat Lazio 2-0 in Serie A on Saturday to strengthen their claim for a place in European football next season.
The Brazil midfielder and Poland winger netted either side of the break in Rome as they moved a point clear of Como in the UEFA Conference League qualifying spot.
Maurizio Sarri's Lazio are now nine points off the pace in the race to feature in continental competition.
Como lost 2-1 at struggling Fiorentina earlier in the day in a blow to their hopes.
In the Italian capital, Lazio were without Spain striker Pedro due to an ankle injury, after he scored in last Sunday's 2-2 draw at Juventus.
Raffaele Palladino made three changes to his Atalanta side from Monday's win over Cremonese, with captain Mario Pasalic on the bench, as Ederson was joined in midfield by Marten de Roon.
A tense opening quarter at the Stadio Olimpico was illustrated by two yellow cards for the visitors, with defenders Giorgio Scalvini and Honest Ahanor being booked.
Lazio had the best chance of the first half an hour as Kenneth Taylor forced Marco Carnesecchi into a fine save but it was the visitors who broke the deadlock.
Ederson, 26, stepped up from the spot to put his side 1-0 ahead after Danilo Cataldi handled the ball in his own box.
After the break, Lazio were denied a penalty of their own as VAR turned down claims of an Atalanta handball on 49 minutes.
On the hour, Palladino's outfit doubled their lead thanks to 24-year-old Zalewski after he scored his first goal since September with an effort from the edge of the box.
Lazio's attempted fightback included three efforts from attacker Daniel Maldini but they were unable to stop a second league loss in five games.
Later, Inter host Juve with a chance to stretch their lead at the summit over second-placed AC Milan to eight points.
The pick of Sunday's action is third-placed Napoli welcoming Roma with three points between the sides.