Antonio Di Natale scored his ninth goal of the season to help Udinese beat Roma 2-0 on Friday and return to the top of the Serie A standings.
Di Natale broke the deadlock in the 79th minute to move joint top of the league's goalscoring charts and Mauricio Isla sealed the victory two minutes from time with a simple finish.
Udinese now has 24 points, two more than Juventus and Lazio who face each other Saturday evening.
Roma, which remains fifth on 17 points, was clearly missing captain Francesco Totti who limped out of training Wednesday with an ankle injury.
The capital side struggled to create chances in a tight game, in which neither goalkeeper was really tested.
Roma's best chance came at the end of the first half but Miralem Pjanic fired wide with only the goalkeeper to beat.
Udinese has turned the Stadio Friuli into somewhat of a fortress and came into the game on the back of seven consecutive victories at home.
Guidolin's team also has the best defense in the league, having only conceded six goals all season - with just one of those coming at the Friuli.
So it was little surprise that Roma struggled to get a sight of goal.
Udinese should have taken the lead in the 26th minute when Pablo Armero's through ball found Di Natale in the middle of the area, but the club's leading scorer hit a rare wayward shot, which flew wide of the right upright.
Both goalkeepers were largely reduced to the role of spectators. The first time either of them was called into play was in the 41st minute when Roma's Maarten Stekelenburg easily prevented Almen Abdi's snap shot from the edge of the area from going into the bottom left corner.
Roma came close to going in front in first-half stoppage-time when Pjanic broke clear and raced down the pitch. The Bosnia and Herzegovina midfielder found himself one on one with Udinese goalkeeper Samir Handanovic but fired wide of the right hand post.
Roma could have broken the deadlock immediately after the restart as Handanovic did well to keep out Daniele De Rossi's powerful 30-yard effort. Juan then saw two headers saved in quick succession.
Luis Enrique's team went close again on the hour mark as Pablo Osvaldo managed to fire a shot through a crowd of bodies in the area but it flew over the crossbar.
Udinese took the lead 11 minutes from time. Giampiero Pinzi lofted a ball over the Roma defense and Di Natale beat Simon Kjaer and nodded down the ball before firing it past Stekelenburg from just inside the area.
Isla made sure of the points following a fine counterattack from Udinese. Armero raced down the left flank before crossing for the Chile international to tap it into an empty net from four yards.
