Inter Milan were held to a surprise 1-1 home draw by Torino as the champions and leaders failed to fully take advantage of Juventus's slip the day before.
Inter could have gone nine points clear with victory in what looked on paper an easy home win following Juve's shock 3-2 reverse at home to Cagliari, but instead have to settle for a seven-point buffer from the rest of Serie A. If AC Milan win at Lazio in the day's late game, they can move ahead of Juve and cut Inter's lead to just six points.
Inter endured a frustrating first 45 minutes as they struggled to break down stubborn opponents. They only had one clear sight of goal when Julio Cruz brought a fine save out of Matteo Sereni on 35 minutes from a firm header.
If Mourinho's team needed a boost to spark them into life, they got it at the start of the second half as Davide Santon failed to close down Blerim Dzemaili on Torino's right. The Swiss midfielder crossed into the box where Ivan Cordoba was left strangely flat-footed and former Manchester City forward Rolando Bianchi arched backwards and steered a header past Julio Cesar, though it was close enough to him that the Brazilian goalkeeper should at least have got a hand to it.
Sereni came to Torino's rescue again on 51 minutes when he tipped away a fine attacking header from Cordoba, but the visitors did not hold out for much longer. And this time Sereni was at fault as he came for, but failed to reach a corner, allowing Nicolas Burdisso to head home from little more than six yards out.
Brazilian right-back Maicon then came within whiskers of burying a rocket from distance that sailed just past the post. Inter started knocking harder on the door late on as they looked for a winner, but substitute Hernan Crespo spooned a shot onto the roof of the net and Ricardo Quaresma fired his effort too close to Sereni.
With five minutes left Sereni turned a Crespo header onto the post as Inter piled forward and forced a succession of corners. And the hosts came even closer again in injury time as Zlatan Ibrahimovic also hit the post before Sereni smothered Esteban Cambiasso's follow up.
Criscito delivers for Genoa
In other action, Genoa tightened their grasp on fourth and the final UEFA Champions League qualifying place as Domenico Criscito scored two minutes from time to give them a 1-0 home win over Palermo.
Roma's charge up the table was blunted at Reggina despite a brace from Chile midfielder Claudio Pizarro, as they were held to a 2-2 draw. It was only the third time in their last 12 matches that they had failed to win and leaves them three points behind Genoa.