The defending league champions and this season's leaders suffered their first defeat of the campaign in all competitions – a 1-0 loss to Atletico Madrid - in the UEFA Champions League on Wednesday.
A day earlier, Roma - who have also won all five of their Serie A matches - were unfortunate not to get more than a 1-1 draw in their trip to Manchester City.
Juve are yet to concede in Serie A and have netted 10, while Roma have scored nine times and conceded just one.
Despite his team's loss in Madrid, Allegri said they would remain positive heading into the home clash against Roma.
“Juve arrive in good shape, as we won all five in Serie A and still haven’t conceded there," he said on Wednesday.
"It will certainly be a great game and tonight's defeat will not change the atmosphere in the team."
Roma will need to be wary of Carlos Tevez, who has an equal league-high four goals this campaign.
Elsewhere, Udinese – whose only loss came against Juve – will be confident of claiming another win when they host Cesena.
Both Milan clubs desperately need wins to stay in touch with the top three.
Filippo Inzaghi's sixth-placed Milan will look to end a three-game winless league run when they welcome Chievo to San Siro on Saturday.
As for Inter, Walter Mazzarri will hope to see a response to his side's thrashing by Cagliari when they travel to mid-table Fiorentina.
Under-fire Rafael Benitez and his Napoli side host Torino, with only a win likely to ease the pressure on the Spaniard.
Cagliari could build on their Inter win with another at Hellas Verona and strugglers Palermo and Empoli are searching for their first victories when they meet.
Bottom side Sassuolo would surprise if they claimed their first win of the campaign at Lazio, while Antonio Cassano - who has scored four league goals - needs to inspire lowly Parma at home to Genoa, and fourth-placed Sampdoria host Atalanta.
