Udinese stifled the threat of Serie A's most prolific striker to take all the points points from Fiorentina's visit to Stadio Friuli.
Italy international Giuseppe Rossi has been in searing form this season, scoring 11 goals in 12 league games to lift Fiorentina to fifth, but he was barely given a sniff on Sunday afternoon as Udinese earned a first clean sheet in six games in a 1-0 win.
Udinese's defensive steel meant Thomas Heurtaux's first-half goal was all that was required to secure a first win in three, while defeat for La Viola snapped a run of three straight wins in all competitions.
Udinese bossed the contest from the opening whistle, with Andrea Lazzari and Borja Valero both having efforts on target inside the first 15 minutes.
Fiorentina's best spell of the opening half - and the whole match as it would transpire - came in a two-minute spell just before the half-hour as first Juan Guillermo Cuadrado and then Alberto Aquilani were both denied by fine Zeljko Brkic saves.
Brkic's heroics looked all the more vital in the 34th minute when the hosts went ahead, Antonio Di Natale crating the chance with a cross than was touched on by Roberto Pereyra to the far post where Heurtaux dived in to head home.
The second half was all about Udinese with the visitors - the off-colour Rossi among them - reduced to a string of hopeful efforts from distance.
The action at the other end was rather more fraught, with Fiorentina goalkeeper Neto forced to save from Di Natale and twice from Luis Muriel, before Silvan Widmer missed a glorious chance to increase the margin of victory in injury time when he somehow skewed wide from close range.