A late Joaquin header gave Fiorentina victory at the San Paolo after Faouzi Ghoulam left Napoli with 10 men for almost an hour.
The result leaves the Partenopei with only a seven-point advantage over the Viola for that last Champions League spot.
This was an early taster of the Coppa Italia Final in May and arrived just three days after both crashed out of the Europa League despite strong performances. Borja Valero returned from suspension, though David Pizarro and Anderson joined Giuseppe Rossi on the treatment table. The hosts missed Christian Maggio, Juan Camilo Zuniga and Rafael, so the versatile Henrique moved to centre-back.
It was also third against fourth and the Viola had the chance to consolidate their position after Inter lost at home to Atalanta this afternoon.
Lorenzo Insigne’s early pull-back was pushed back into the middle, but Gonzalo Higuain handled on the follow-up. On eight minutes Higuain ran on to a smart ball over the top and let it bounce, forcing an acrobatic Neto save on the half-volley to palm it out from under the bar.
Insigne also set up Marek Hamsik down the left, but his shot was beaten away by Neto at the base of the near post.
Neto kept his cool to rush off his line and slide the ball off Hamsik’s feet in the penalty area, as the Slovakian appeared to jump out of the way.
There was controversy on 37 minutes when Marko Bakic burst forward following a Raul Albiol error and was brought down on the edge of the box by Faouzi Ghoulam. The referee opted for a red card for ending a clear scoring opportunity, but replays suggest the former Saint-Etienne full-back may well have got the ball.
It wasn’t the first controversy, as earlier this season Juan Cuadrado was sent off for simulation in stoppages during Napoli’s 2-1 win when he should’ve received a penalty.
Napoli continued to push with 10 men, as Neto fingertipped an Insigne free kick over the bar. Stefan Savic needed a crucial intervention to stop Higuain tapping in from eight yards.
Josip Ilicic replaced Bakic, who was feeling the effects of that red card challenge. Insigne was tripped by Gonzalo Rodriguez when sprinting towards the area, but there were other players covering so it was only a booking.
Cuadrado went close with a chest and volley just over the bar, while Alberto Aquilani, Cuadrado and Insigne fired off target from distance.
Insigne ran on to Higuain’s through ball and spun a defender, but another rushed in behind him for a decisive block.
Jose Callejon saw Neto off his line and attempted an audacious lob from midfield, which saw the goalkeeper back-pedal furiously to pluck it out from under the bar.
Callejon also tested the goalkeeper at the near post, but he was acting as right-back when down to 10 and couldn’t get back in time to stop Cuadrado setting up Ilicic, but the Slovenian hit the side-netting from six yards.
Aquilani’s low drive was dealt with by Pepe Reina, as was a deflected Gokhan Inler attempt from distance for Neto.
Alessandro Matri replaced Mario Gomez and should’ve scored straight away, but he fired straight at Reina from close range.
Moments later his free header from six yards was wide on a Joaquin cross from the right.
Dries Mertens came off the bench, but lasted under 10 minutes before he sprained his ankle when cleanly tackled by Savic, as he fell awkwardly.
Ilicic blasted just over the bar, but Fiorentina did find the breakthrough late on at the Stadio San Paolo.
Matri drew Reina away and pulled back for Manuel Pasqual to cross it to the back post, where Joaquin was waiting with the free header.
Reina rushed out to stop Matri in a one-on-one in stoppages.
Sent off: Ghoulam 37 (N)