Edy Reja's men are just two points behind Inter in fifth in Serie A, and a prospective UEFA Europa League berth.Rafa Benitez's Napoli, meanwhile, are hovering somewhat aimlessly in third spot, with unrealistic chances of catching second side Roma or slipping beneath fourth-placed Fiorentina.
Roma are 12 points clear of the Naples outfit with six games to play, while Benitez's side are nine points ahead of their Florentine rivals in the race for the last UEFA Champions League spot.
And Fascetti said Lazio have more to play for.
"It will be a very intense weekend," Fascetti told Radio Marte.
"Inter have a tough trip to Genoa to play Sampdoria and Fiorentina play Verona.
"A positive result for (Andrea) Mandorlini's boys (Verona) could put the Viola (Fiorentina) under pressure for the rest of the season.
"Thinking about Sunday's match, at the moment Lazio have more motivation.
"They are having a good period and the fact they have a serious target to go for could play a decisive role in the outcome of the match."
Fascetti, 75, coached Lazio from 1986-88, and also played 12 games for the club in 1964-65.
"Thinking about Sunday's match, at the moment Lazio have more motivation.
"They are having a good period and the fact they have a serious target to go for could play a decisive role in the outcome of the match."
Fascetti, 75, coached Lazio from 186-88, and also played 12 games for the club in 1964-65.
