The Red Devils looked to be heading for an embarrassing defeat in the derby following goals from Vincent Kompany and Ilkay Gundogan in the first half at The Etihad.
However, Paul Pogba scored two quick-fire goals in the second half to level up the derby clash before Chris Smalling netted the winner from the set-piece.
Manchester United are in second place and 13 points adrift of Manchester City following a one-sided title race this season.
The Red Devils haven’t won the Premier League title since 2013 when Manchester United legend Sir Alex Ferguson was still in charge at Old Trafford.
Jose Mourinho signed Chile international Alexis Sanchez in a swap deal from Arsenal in the January transfer window.
However, the 20-time English champions will surely need more additions to challenge Manchester City next term given their dominance in the 2017-18 season.
Former Liverpool FC captain Souness claimed that Manchester United have made a big statement ahead of next season.
“They put a marker down today, for next season most definitely,” Souness told Sky Sports.
“They were dogged and determined and came back from being on the ropes big time to beat Man City and they’ve shown other teams how to do it.”
Manchester United won the Europa League and the League Cup last season after the Red Devils limped to a sixth spot in the Premier League table.
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