Rivals Lecce won 2-0 at already-relegated Bari in a fiery local derby, including minor crowd trouble. to help condemn Sampdoria with one round of matches still to play.
The Genoa side, last relegated in 1999, started the season in the Champions League qualifiers but sank like a stone after selling top strikers Antonio Cassano and Giampaolo Pazzini in January when they were in comfortable midtable.
"We must acknowledge the errors and assume the responsilbity for all the mistakes that were made," Edoardo Garrone, son of owner Riccardo, told reporters.
"The only thing I can say is that the family will stick with Sampdoria."
Lazio's city rivals AS Roma are now out of the running for fourth after Alejandro Gomez's stoppage-time strike sealed a 2-1 win for Catania and potentially ended interim Roma coach Vincenzo Montella's hopes of the job fulltime.
They went behind on halftime to Fabrizio Miccoli's goal but Jonathan Biabiany, one of a number of forwards who have failed to adequately replace AC Milan's Cassano and Inter's Pazzini, equalised soon after the break.
Sampdoria captain and Italy midfielder Angelo Palombo sobbed on the pitch at the end and went to apologise to the main group of ultra fans, who unsuccessfully demanded that owner Riccardo Garrone also come "in front of the stands" to say sorry.
