First-half goals from Mauro Icardi and Marcelo Brozovic sealed a comfortable 2-0 win for Inter Milan over second-placed Napoli in Serie A.
A dominant display at the San Siro saw Roberto Mancini's side close the gap on Roma to three points in the race for a Champions League spot, while Napoli's title challenge faltered with a second loss in three.
The absence of top scorer Gonzalo Higuain was expected to hurt Napoli, but it was their defence that proved their undoing early on as Icardi opened the scoring with his 15th of the season.
In just the fourth minute the Argentina striker raced onto a lofted through ball from Gary Medel and brought the ball down expertly with his left foot before a neat lofted finish with his right to go one up, with Pepe Reina and his defence left incensed at the lack of an offside flag.
The visitors gradually began to assert themselves, but the absence of Higuain showed as they struggled to make any kind of impression in front of goal.
However Samir Handanovic was fortunate to see Marek Hamsik's long-range effort bounce to safety after he made a meal of a straightforward save, pushing the ball back out into a vacant penalty box.
He was called upon again minutes later, but this time was up to the challenge as he acrobatically leapt to tip Allan's strike over the bar.
Inter responded with some pressure of their own, and after Medel saw a shot saved by Reina, Stevan Jovetic fired straight at the former Liverpool man after a fine piece of play down the left from Ivan Perisic.
The roles were reversed moments later as Jovetic turned provider to tease a cross into the back post, only for Perisic's stooping header to drift wide with the goal gaping.
The lead was doubled on the brink of half-time when Jovetic again found space and Icardi beat the offside trap once again before teeing up Brozovic, who lifted the ball beyond Reina in similar fashion to the opener.
Maurizio Sarri began to chase the game after the break and sent on Dries Mertens, who almost made an immediate impact, his cross finding Jose Callejon who volleyed narrowly past the post with Handanovic beaten.
Jovetic nearly got his name on the scoresheet on the hour mark with a lob from outside the area after Reina had punched clear, but Kalidou Koulibaly was on hand to head the ball off the line.
Handanovic was again alert to prevent Callejon tapping in late on but in the end Inter eased to a comfortable win that leaves Juventus in pole position to claim the Scudetto.