Ulster SFC: Donegal hit four goals to stun champions Derry
Jim McGuinness further enhanced his reputation as one of the greatest managers in the modern era by leading Donegal to a stunning 4-11 to 0-17 triumph over Derry in Celtic Park.
Donegal powered home with three second-half goals to end Derry's attempt to win three Ulster titles in a row.
Daoire O'Baoill chipped Odhran Lynch twice before Jamie Brennan and Oisin Gallen goals sealed a memorable win.
Donegal will play Tyrone or Cavan in the Ulster semi-final next Sunday.
History repeats itself for Harte
Derry have a month to regroup for the All-Ireland series after McGuinness inflicted another horrible déjà vu moment on Derry manager Mickey Harte, who is yet to beat the Donegal maestro in championship football.
McGuinness defeated Harte's Tyrone team in the Ulster Championship three years in a row from 2011 to 2013.
McGuinness' return to the Donegal sideline for the first time in 10 years, allied to Tyrone legend Harte's surprise appointment as Derry boss this year, meant that their collision in this Ulster Championship first round clash was always going to be a fascinating prospect.
And the game itself did not disappoint.
A high-octane, high-quality encounter was bossed mostly by the Division Two champions who dropped very deep, broke at speed and were still able to mark the Division One champions' best players out of the game.
Conor Glass and Shane McGuigan, so often key men during Derry's marvellous run over the last few years, were peripheral figures and there was no Plan B as Donegal streaked clear.
They turned a narrow 1-7 to 0-9 interval lead into an impressive six-point victory that will live long in the memory of the 14,714 packed inside Celtic Park.
