Pep Guardiola praised Sergio Aguero after his man-of-the-match.
The Argentine striker has scored four goals in his last two games to take his season tally to 22 and bagged a brace against Huddersfield Town, as well as creating another for Pablo Zabaleta.
Guardiola admitted he couldn't be happier.
"It’s the best performance I’ve ever seen from Sergio," said Pep. "He scored two goals and created a lot of chances. When he plays at that level, he’s unstoppable. We are so happy with how he played today.
"We scored five goals again, chances arriving and attacking. The people enjoy the way we play. I know how complicated the competition can get when you play teams in the Championship. If we are able to win against Middlesbrough, we’ll play the semi-final at Wembley. We came back from Abu Dhabi but we continued in the same way.
"We are what we are, it’s better for us not to compare us with other sides. I think the team makes a good performance when we beat the best team in the world in Barcelona.
The City boss also had praise for youngster Aleix Garcia, who played the full 90 minutes in a slightly deeper holding role.
He said: "Aleix played really well tonight. He was a little bit shy at the beginning, but he’s a player with something special. I’m really pleased with his performance.
"The performance from Claudio Bravo was amazing, too. He helped us build up well and his moments and his saves gave us the continuity to play. I know I can count on him. I want to congratulate him on how he played at Huddersfield and how he played today. Also Gael Clichy did really well.
"We are still in the process of growing. I see many good things. We are repeating many good things game by game. I was impressed with Huddersfield. Sometimes in this period of the year, some of the top teams in the Championship are more dangerous than some in the Premier League. From the beginning, we had a lot of energy and we were aggressive without the ball.
"Tomorrow we’ll analyse our game and look at Sunderland and then decide the line-up. for the game."
Pep had a final world for his friend and former team-mate Luis Enrique who will step down as Barcelona boss at the end of the season.
He said: "As a Barcelona fan, I’m sad that we’ll miss the perfect trainer for Barcelona. His three years has played unbelievable football. I understand him completely and I wish him the best.
"From a membership point, I’d like to thank him for all he’s done for the club. There are few better managers in the world than Luis Enrique. I still think they are the best team in the world. I’m upset he’s not going to be there anymore, but I wish him the best."