Napoli moved into third place in Serie A on Saturday after a 2-2 draw at Roma, but their hopes of making the Champions League next season were left on a knife-edge.
Napoli have 55 points, but will slip back to fourth on Sunday if Lazio avoid defeat against Udinese with three games left to play.
Juventus and AC Milan already have the top two automatic qualifying places for the Champions League wrapped-up.
Napoli had to settle for a point when Brazilian Simplicio struck three minutes from time for Roma who remain seventh in the table, four points off the crucial third place.
Napoli thought they had the game won when Uruguayan striker Edinson Cavani struck a superb 67th-minute free-kick from 25 metres which beat Roma's Romanian goalkeeper Bogdan Lobont.
Roma had dominated large parts of the first half with Fernando Gago almost beating Napoli keeper Morgan De Sanctis who had saved from Francesco Totti in the 27th minute.
But they took a deserved lead in the 41st minute when Brazilian Marquinho hit the target from a cross by Aleandro Rosi.
Napoli levelled four minutes into the second period through Colombian star Juan Zuniga.
Despite Simplicio's late equaliser for Roma, the Olympic Stadium crowd jeered their team off the pitch as their Champions League hopes disappeared.
Catania's outside hopes of playing in the Europa League next season suffered a setback when they were held to a 1-1 draw by Palermo in the Sicilian derby.
The draw kept Catania in eighth place, five points off their sixth-place target.
Catania opened the scoring in the 25th minute through defender Nicola Legrottaglie but Palermo levelled just after half-time when skipper Fabrizio Miccoli found the target.
Source: AFP Global Edition
