A superb first-half volley from veteran Udinese striker Antonio Di Natale secured a precious 1-0 win over Lazio and dented the Biancocelesti's hopes of European football next season.
With only three points separating the sides and a place in Europe within sight, there was plenty of incentive for Udinese especially against a Lazio side which had won only twice in their past 12 league games.
Lazio are now sixth, one place outside of Europe, but on the same points (51) as seventh-placed Udinese.
Lazio lined up with German striker Miroslav Klose but left Brazilian midfielder Hernanes on the bench until coach Vladimir Petkovic sensed the danger midway through the second half.
Klose, however, made little impact as a better organised Udinese side went about claiming their third consecutive league victory at home against the visitors -- the first time they have won three league matches consecutively this season.
After a balanced opening Udinese steadily began to threaten and were rewarded with Di Natale's opener on 19 minutes.
Lazio's defenders failed to deal with a nice exchange on the left between Gabriel Silva and Roberto Pereyra, but the centre-backs were at even more fault when Pereyra's ball was flighted into the area.
Both defenders left Di Natale, returning to Francesco Guidolin's side following a recent ban, on his own and the striker produced a superb angled volley to leave Federico Marchetti rooted to the spot.
Lazio produced few real chances in the opening half.
Antonio Candreva's cross for Klose was a metre too far in front of the German and then Cristian Ledesma's near-post effort was blocked.
Udinese threatened again from a corner on the half hour, and when the ball went out for another corner Marchetti had to scramble amid a gaggle of Udinese heads to collect.
Lazio had little response in the immediate exchanges after the break and a schoolboy error by Lazio defender Andre Dias on the hour gave Dusan Basta the chance to beat Marchetti only for the Serbian's effort to sail wide.
Petkovic made two changes on the hour mark with Hernanes and Ederson coming off the bench to replace Ledesma and Lithuanian Marius Stankevicius respectively.
Almost immediately, however, Udinese threatened when Polish teenager Piotr Zielinski laid off for Di Natale only for the veteran to skew the ball just wide of the post with the outside of his foot.
Ederson and Hernanes' arrival almost paid off but the former could only send his effort wide after Hernanes had left the a loose ball in his path after tumbling on his way towards goal.
Udinese replied moments later, but despite Zielinski doing well to create space for Di Natale the striker lost possession while in an optimal scoring position when the ball bounced wildly.
Earlier Saturday Genoa spurned the chance to move out of the relegation zone in a 1-1 draw at home to Atalanta.
Antonio Floro Flores opened the scoring for the hosts after just six minutes but Atalanta were level only two minutes later thanks to defender Cristiano Del Grosso.
Genoa came back into the match after the introduction of Ciro Immobile in the closing stages, but several efforts from the striker were blocked or were off target.
Leaders Juventus, who hold an 11-point lead over Napoli, will look to take another step towards their 29th league title at home to AC Milan on Sunday when Napoli host Cagliari.