Two first-half goals condemned Sampdoria, who were left 13 points from safety with four rounds remaining.
Spezia and Cremonese are the other teams in the relegation zone and they are three and six points, respectively, behind 17th-placed Hellas Verona.
Sampdoria, who won just two matches since the start of the year, were behind on Monday in under minutes.
Festy Ebosele ran almost the entire length of the field before sending the ball through to Roberto Pereyra, who lifted it above goalkeeper Nicola Ravaglia.
Adam Masina doubled Udinese's lead in the 34th when he headed in a chipped pass from Sandi Lovric.
Samp almost got back into the match 12 minutes into the second half, but Manolo Gabbiadini's effort came off the right post.
AAP
