Sergio Aguero came off the bench to score the winner as Manchester City beat Sheffield United 1-0 at Bramall Lane on Tuesday.
Gabriel Jesus had seen his first-half penalty saved by Manchester United loanee goalkeeper Dean Henderson but Aguero replaced him to win the game for City late on.
Pep Guardiola's side are now 13 points behind league leaders Liverpool who have two games in hand while Chris Wilder's men remain in seventh place.
"Sergio is on fire right now. Strikers need momentum. It's good for us to have strikers in this form," said Guardiola. "I am so happy with the team. I know what it's like to play here, it is a tough, tough place. We controlled it well and in the end we created chances to win.
"It was an incredibly good victory for us to take a step towards securing Champions League football next season."
City were boosted with the return of defender Aymeric Laporte, who started his first game for the club since suffering a knee injury in September.
"We knew that Aymeric couldn't play for 90 minutes, that's why we played five at the back to protect him a little bit. He's a crucial player for us, we've missed him, it's good for us to have him back," said Guardiola.
The visitors had the first chance of the match after 19 minutes when Riyad Mahrez set up Raheem Sterling in the box but Henderson produced a great save to deny the forward. Henderson was also alert to a Nicolas Otamendi overhead kick moments later.
City were awarded a penalty 10 minutes before the break when Chris Basham brought down Mahrez in the box but Jesus was denied by Henderson. The goalkeeper stepped off his line before the kick but VAR didn't intervene.
The hosts had the better opportunities in the second half when Lys Mousset failed to convert with a close range backheel while Oliver McBurnie came close to reaching an Enda Stevens cross.
City took the lead after 73 minutes when Aguero got on the end of a wonderful Kevin De Bruyne cross to tap into an empty net.
"Kevin De Bruyne has found an amazing pass and the movement of Sergio Aguero, he's done that to everyone in Europe and the world. It's a great finish. After that we're behind and it's double difficult for us," said United manager Wilder.
"I've got nothing but an enormous amount of pride for my team. We went toe-to-toe with them. When opportunities arise you have to show a little bit of quality and we didn't do that sadly.
"Games like this are what we're here for. We've worked really hard to get here, we want no regrets and I don't think there were tonight."