Manchester United shocked rivals Manchester City by winning 1-0 at The Etihad.
Teenage striker Marcus Rashford scored the goal in the first half, and United made life difficult for a City side who were missing captain Vincent Kompany.
Rashford now has five goals in eight games for the Red Devils, scoring at the perfect time, just as many were beginning to wonder if he should be handed a rest.
Manchester City pushed hard to try and break United down, with playmaker David Silva even creating six chances, but it was to no avail as the Red Devils stood firm.
Former United defender and Champions League winner Rio Ferdinand was impressed with the performance, particularly in the first 45 minutes.
@ManUtd please make the 1st half a sign of things to come in an attacking sense. Derby day win....happy days— Rio Ferdinand (@rioferdy5) March 20, 2016
Louis van Gaal's side have struggled for consistency this season and still face a fight to finish in the top four, but this is a performance which gives them hope, if they do not lose the momentum they have gained, after the international break.
United are now just one point behind City in the race for fourth spot, with Manuel Pellegrini's side also having a Champions League quarter-final tie to contend with, while West Ham are also in the mix.