Inter Milan surged three points clear at the top of Serie A after a sublime double from Zlatan Ibrahimovic sealed a 2-0 win at Palermo on Saturday.
The champions again failed to find their best form and relied on two moments of brilliance from the Swede, who first netted off the post with a swerving 20-metre shot just after halftime.
He then blasted in an unstoppable free kick after 62 minutes to stun the Sicilians, who had been livelier in attack than the defence-minded visitors in the first half.
Juventus, who meet Inter next weekend, had joined their rivals at the top on Thursday following a 4-1 win over Genoa.
AC Milan and Napoli can go above Juve and move within a point of the leaders if they beat Chievo and Atalanta respectively on Sunday (1400 GMT).
Lazio will be two points behind with a victory over struggling AS Roma in the Rome derby (1930).
"Today I've scored two important goals. We've won a difficult away game against Palermo who are a tough team. I'm very happy," Ibrahimovic said. "Juventus will be a hard game but if we want to take the championship we have to win."
Inter coach Jose Mourinho, who left out under-performing wingers Ricardo Quaresma and Mancini, is struggling to find the right balance in his side and started with four central defensive midfielders strung across the park.
They did not support isolated strikers Julio Cruz and Ibrahimovic in the first half but the latter battled hard to create what he could, going very close on one occasion.
Forward Fabrizio Miccoli had three half chances for mid-table Palermo but they were soon blown away by Ibrahimovic's sixth and seventh league goals this term, with the former Ajax Amsterdam and Juve striker unlucky not to claim a hat-trick.