Fabio Liverani's game plan was to frustrate the hosts. For 79 minutes they did just that, until the unlucky substitute headed Antonio Di Natale's free kick into his own net.
The result sees Udinese stretch their unbeaten home run to an impressive 21 games. Coming into the game, Francesco Guidolin was still without the injured Zeljko Brkic and Maurizio Domizzi, although Giampiero Pinzi was back on the substitutes bench.
Thomas Heurtaux forced Genoa's Mattia Perin to palm a point blank effort off the line on 15 minutes. Not long after, the shot stopper was beaten at full stretch, as Maicousel's curler from the edge of the D went just past the post.
Ivan Kelava was largely a spectator in the Udinese goal as Genoa struggled to create anything meaningful going forward. When Moussa Konate found space down the right hand side, Kelava tipped his effort around the post.
Di Natale had the ball in the net after half an hour, but the effort was rightly ruled out. The frontman was standing offside after Emmanuel Badu's scuffed shot trickled through to him.
Udinese failed to make a plethora of first half corners count. Danilo wasted a free header after a cross found the Brazilian defender unmarked deep in the Genoa box.
Five minutes before the break, Badu beat his marker, only for Roberto Pereyra's audacious backheel to deflect off a defender's legs and trickle wide. Right on half time, Perin comfortably caught Di Natale's first time shot. The veteran took aim at the near post, but didn't put enough power in his shot to sufficiently test the Genoa custodian.
Guidolin threw on Luis Muriel early in the second half to provide more attacking impetus. Di Natale saw a set piece deflect over. Naldo nodded the resulting corner wide, with Perin rooted to the spot.
Badu was denied a penalty after a clash of shoulders with Daniele Portanova in the box. Udinese continued to pour forward in search of that elusive goal. Allan sliced a shot wide after space opened up for the defender to run into.
Luis Muriel drew gasps from the crowd as he drove in from the left and cut inside Alessandro Gamberini, before sending a vicious drive just past the post. Moments later, Naldo fired over after trying his luck from 30 yards.
Udinese got the goal they deserved 11 minutes from the end. Portanova barged into Luis Muriel to give away a needless free kick. Di Natale floated the ball into the box and Calaio unwittingly sent a powerful header past Perin.
Udinese: Kelava; Heurtaux, Danilo, Naldo; Basta, Badu, Allan, Pereyra, (Lazzari 86) Gabriel Silva; Maicosuel, (Luis Muriel 54) Di Natale (Zielinski 90)
Genoa: Perin; Gamberini, Portanova, De Maio; Vrsaljko, Cofie, Lodi, Bertolacci, (Biondini 67) Antonini; (Stoian 83) Konate, (Calaio 62) Gilardino
Goals: Calaio og 79 (U)