Juventus's march towards a seventh consecutive Serie A championship was stalled by a goalless draw at struggling SPAl that kept the suspense alive in Italy.
Massimiliano Allegri's side had been bidding to open a seven-point cushion on Napoli, who can now close the gap to two when they host Genoa on Sunday .
Juventus's 12-match league winning streak came to a halt but they matched their own Serie A record of 10 games without conceding a goal.
The champions lacked inspiration against the promoted side from Ferrara, to the north of Bologna, with normally reliable goal machines Paulo Dybala and Gonzalo Higuain failing to fire.
It was the first time in nearly 50 years that Juventus had played in Ferrara and they came up against a solid and well-organised SPAl unit.
Juventus almost scored in their first attack of the night when a Douglas Costa solo run created space for fellow Brazilian Alex Sandro but his effort was deflected wide.
Dybala tried his luck after 17 minutes with a long-range curling effort that flew wide.
There was also a worry three weeks before their Champions league quarter-final first leg against Real Madrid with Giorgio Chiellini leaving the pitch 10 minutes before the end with a thigh injury which Allegri later said was "muscle fatigue".