Sergio Aguero came off the bench in the second half to tally the winning goal 12 minutes from time as Manchester City secured a 2-1 win over Manchester United at Old Trafford on Monday.
James Milner broke the scoreless deadlock in the 51st minute for City, while Vincent Kompany's own goal eight minutes later brought United back to level terms.
However, Aguero entered the contest in the 71st minute, and seven minutes later, netted the decisive goal to give City a measure of revenge for United's 3-2 victory at the Etihad Stadium earlier this season.
Despite the result, United still owns a 12-point lead at the top of the Premiership table over City with seven games to play.
City asked most of the questions in the first 20 minutes of the match, but United nearly went on top just before halftime when Robin van Persie knocked a ball down inside the penalty area for Rafael, whose first-time effort clipped the post.
The visitors snatched the lead six minutes after halftime through Milner, who took a pass from Samir Nasri and fired a first-time shot toward goal that took a slight deflection on its way past goalkeeper David De Gea.
United answered in the 59th with a bit of help from Kompany as Van Persie's right-wing free kick was played to the front of goal, where goalkeeper Joe Hart failed to deal with the ball, allowing Phil Jones to head it off the back of Kompany and into the net.
The game was there for the taking as it entered the final 20 minutes, but Aguero provided the one moment of brilliance needed to separate the sides as he took a pass near the edge of the area, eluded three United defenders, and smashed a shot into the roof of the net past De Gea from eight yards.