It was a stunning second-half comeback from Manchester United as French midfielder Paul Pogba netted a double and Smalling himself scored the winner with a volley.
Man United were woeful for a half-hour period in which Man City struck two past David de Gea and dominated the game. Maintaining possession and creating chances became a huge issue for United.
Two early second-half goals from Pogba changed that. Smalling revealed it took words from manager Mourinho to change United’s performance.
“Coming in at half time a lot of us were feeling sorry for ourselves. We had to show pride,” Smalling said.
“The first half was terrible. We knew it wasn’t good enough.”
Mourinho reminded his United players of the need to stop their rivals winning the title against them.
“Jose emphasised we didn’t want to see the crowds watching them celebrate their title.”
Smalling himself was an unlikely scorer of the winning goal having had a poor game earlier on in which he allowed Vincent Kompany to escape his attention and score the opening goal.
“When you make a mistake, you want to have an opportunity to make amends,” the defender continued. “I was thankful and you could see the relief on my face.”