Manchester City boss Pep Guardiola said his players can do much better despite a record-breaking 5-0 win over Sporting CP in the first leg of their Champions League last-16 tie on Tuesday.
City became the first team in Champions League history to lead an away knockout match by four goals at the break after a brace from Bernardo Silva and strikes from Riyad Mahrez and Phil Foden.
Raheem Sterling added a sublime fifth after the interval as City racked up the joint-biggest winning margin in a Champions League knockout game.
It was also the Premier League champions' biggest ever win in an away game in any round of the competition.
While acknowledging his side's ruthlessness in front of goal, Guardiola did criticise his side for giving the ball away cheaply.
Asked if it was a perfect performance, Guardiola told BT Sport: "No. Some players underperformed and we lost easy balls, but we were so clinical.
"We saw in the first five or six minutes how good Sporting are. The difference between the two teams is not 5-0 but we were so clinical. We punished them.
"There is one rule in football when you have the ball and that's not to lose it. We had some simple passes that we lost. Against the top sides in Europe we would be punished.
"It's just a game with a fantastic result. We have one more game to be in the quarter-finals and this is what you want but the players know with me and the way we work that we can do better.
"I'm incredibly happy, please don't misunderstand me, but we can do better."
Lisbon-born Silva, who started his career at Sporting's city rivals Benfica, registered his first goals in the Champions League since netting in the last 16 in last year's competition.
Indeed, five of his eight Champions League goals for the Citizens have come in this round.
But despite City's commanding lead, the 27-year-old insisted they will not take next month's second leg lightly.
"I am Portuguese and I'm from the other side of the city so it was special to score here in my hometown," he said.
"It was nice to start the last 16 with a 5-0 win. It's always an extra motivation to come here to Lisbon in such an important game. There is still a job to do in Manchester. We cannot relax.
"It was a very good performance. In the first half we were in that mood to win 4-0. We were a bit sloppy which gave them the opportunity to counter-attack but we were very clinical.
"You need some luck as well. We are very happy with the win. To win 5-0 away is a great result and it's a great performance.
"Sometimes you play better than we did in that first half and we have gone in 0-0. We can always still improve."
City are next in action on Saturday when they host Tottenham in the Premier League.