Preston continue their struggle at the foot of the Championship after being blown away at home to Bristol City.
Debutant Eddie Johnson fired over for the hosts but City raced away to score the opener on five minutes when Andy Keogh tucked in Steven Caulker's pass.
After the break, David Clarkson nodded in Brett Pitman's cross to make it two.
The Robins pushed on and Clarkson swept in his second after Keogh's shot and Pitman added a late fourth after picking up a pass from Martyn Woolford.
The misery shows no sign of relenting for boss Phil Brown as bottom-of-the-table North End lost for the 17th time in the campaign.
His side were also dealt a devastating blow at half-time with defender Conor McLaughlin suffering a suspected broken leg.
The visitors were impressive but Preston were had their chances as Johnson, making his debut after signing from Fulham on loan late on transfer deadline day, went close early on with a shot from 12 yards.
Nathan Ellington also brought out a stunning save by David James in the 23rd minute.
Having got the all-important goal in the first half, City took full advantage of their increasingly open opponents and Clarkson nodded in their second goal moments after wasting another header.
Ellington was continuing to be a menace to the City defence but Clarkson made sure of the points when he stabbed the ball in after Keogh's shot was saved.
Pitman scored a fourth with five minutes left when he picked up the ball from a Woolford pass to drive in from 18 yards.
