League of Ireland: Derry City 0-5 Dundalk
Derry City captain Ryan McBride was sent-off as the Candystripes suffered a 5-0 hammering by Premier Division leaders Dundalk at the Brandywell.
David McMillan's header and a flicked finish from Dane Massey put the champions 2-0 ahead.
McBride was shown a straight red card for a heavy challenge on Stephen O'Donnell on 28 minutes.
McMillan slotted in and completed his hat-trick after Daryl Horgan fired in Dundalk's fourth goal.
Derry were behind after just 90 seconds with McMillan's header squirming through the legs of keeper Gerard Doherty.
The visitors dominated the early stages but City came to life as Aaron McEneff saw his shot deflected wide before Gary Rogers tipped over a Rory Patterson header.
Champions show class
Massey doubled the lead on 20 minutes after connecting with a free-kick from former City midfielder Patrick McEleney.
McBride's dismissal ended City's hopes and McMillan stroked past Doherty five minutes before the break after the keeper had denied John Mountney.
Substitute Nathan Boyle and Dean Jarvis went close as Derry made a bright start to the second half before Dundalk regained control.
Horgan drilled in from close range after 59 minutes before McMillan secured his treble 10 minutes from time with a fine turn and strike into the top corner.
City remain third but are now 12 points behind an impressive Dundalk outfit.
Meanwhile, next Friday's league game between Shamrock Rovers and Derry has been postponed due to the Dublin side's Europa League involvement.