Pep Guardiola was delighted to see Manchester City overcome a resilient Sheffield United after Sergio Aguero came off the bench to score the only goal of the game.
It had looked set to be an evening of frustration for the Premier League champions at Bramall Lane on Tuesday, with Blades goalkeeper Dean Henderson in inspired form.
Gabriel Jesus saw a first-half penalty saved and Raheem Sterling also missed an excellent chance before Aguero sealed the points, converting Kevin De Bruyne's pinpoint cross in the 73rd minute.
"It's a difficult place to come, they are so physical," Guardiola told BT Sport. "It was a solid performance, we only conceded two chances. In the first half the keeper made two incredible saves.
"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."
Guardiola was able to hand Aymeric Laporte his first start since August following a knee injury, the Frenchman managing 78 minutes in a system designed partly for his benefit.
"We knew that Aymeric couldn't play for 90 minutes, that's why we played five at the back to to protect him a little bit," said Guardiola. "He's a crucial player for us, we've missed him, it's good for us to have him back."
The winning goal came from the most obvious source, with Aguero quickly to the fore after replacing Jesus, who fluffed his lines after Riyad Mahrez had earned a spot-kick.
Aguero surpassed 250 goals for City in the 2-2 draw with Crystal Palace last Saturday and now has eight in his past five outings in all competitions, leading to warm praise from his manager.
"Sergio is on fire right now," said Guardiola. "Strikers need momentum. It's good for us to have strikers in this form."