Champions Inter Milan missed their chance to go top of the Serie A standings when they suffered a 3-0 defeat at Fiorentina in a rescheduled fixture on Thursday as Moise Kean scored twice for the hosts.
The defeat left Inter in second place on 51 points, three behind leaders Napoli, and Fiorentina moved up to fourth on 42 points, ahead of Lazio on goal difference.
The original match on December 1 was suspended when Fiorentina's Edoardo Bove collapsed on the pitch and was rushed to hospital, and the game restarted at 0-0 in the 17th minute with a Fiorentina throw-in.
Fiorentina were under the cosh early on, with keeper David de Gea parrying a shot from Lautaro Martinez, and Carlos Augusto having a goal chalked off for offside, but the two best chances of the opening half fell to the hosts.
Kean got on the end of a Fabiano Parisi cross and his downward header from the edge of the six-yard box brought an instinctive save with his foot from Inter keeper Yann Sommer.
Kean then turned provider, spraying the ball out wide to Dodo who drove forward into the area but pulled his shot wide of the far post, and the game remained goalless at the break.
Inter struggled to get forward and create any real openings early in the second half, and Fiorentina took a deserved lead from a corner in the 59th minute.
Ranieri arrived from outside the area, getting to the ball ahead of Davide Frattesi and hit his shot first time low into the corner.
There was little in the way of response from Inter, and Fiorentina doubled their lead nine minutes later.
Dodo crossed from the right and Kean pulled away from his marker before powering a header into the bottom corner, this time leaving Sommer with no chance.
Inter responded by making three changes, with Nicolo Barella, Federico Dimarco and Marko Arnautovic all coming on, but the move failed to inspire the visitors.
Their only chance smacked of desperation with Dimarco attempting to catch De Gea off guard with a lob from distance, but the keeper got back in time to hold onto the ball.
With time running out, and an Inter comeback looking unlikely, Fiorentina wrapped up the win in the 89th minute, the goal coming from a Dimarco howler.
The defender hit a backpass without looking and Kean was there to capitalise, and with the keeper in no-man's land, the striker finished with aplomb to net his 15th league goal of the season, and end Inter's 17-game unbeaten run in the league.
Inter will have the chance for revenge when the sides meet again on Monday at the San Siro.