Simon Grayson's men had moved up to second in the table prior to the game after taking 16 points from a possible 18.
And Preston ran out 2-0 winners as Callum Robinson and Joe Garner scored in the space of five second-half minutes to condemn their opponents to a third consecutive defeat.
Swindon Town leapfrogged the Dons into third courtesy of a 3-0 win over 10-man Notts County, who had Liam Noble sent off towards the end.
Saturday also saw Tony Mowbray take charge of his first match as Coventry City manager and things started brilliantly for him at home to Port Vale, as James O'Brien scored within four minutes.
However, Vale hit back impressively, goals from Tom Pope, Mark Marshall and Michael O'Connor securing a 3-2 away win that leaves Coventry a point above the drop zone.
Barnsley's rise up the table continued with a fifth straight win, the Yorkshire club beating Walsall 3-0 to join Doncaster Rovers - who drew 1-1 at Gillingham and occupy the final play-off place - on 50 points.
Yeovil Town's bid to avoid the drop received a boost in the shape of a 2-1 victory over Oldham Athletic, though the former remain bottom despite James Hayter's last-minute winner.
The other three teams in the relegation zone all suffered defeat, with Crawley Town and Colchester United going down 2-1 to table-toppers Bristol City and Rochdale respectively and Leyton Orient losing 1-0 at Peterborough United.
Crewe Alexandra managed to open up a seven-point gap between themselves and the bottom three, beating Scunthorpe United 2-0, and a 2-1 triumph over fifth-placed Sheffield United moved Fleetwood Town to within two points of the top six.
