Manchester City manager Manuel Pellegrini underlined the importance of Argentine international striker Sergio Aguero following his hat-trick in the 4-2 FA Cup fourth-round victory over Watford. Aguero took his goal tally to six in four games since his month-long lay-off with a calf injury as City came from 2-0 down to overcome the second-tier club on Saturday and book a place in the fifth round. With a place in the League Cup final secured and a last 16 tie with Barcelona in the UEFA Champions League on the horizon, City remain on course to win four competitions in Pellegrini's first season at the club. And with Aguero having now scored 25 goals in 24 games, across all competitions, it is clear that the in-form forward will be integral to any success City enjoy. "Sergio's a top player, very important for us," said Pellegrini, whose side are currently in second place in the English Premier League. "The first idea was for him not to play 90 minutes because he has been playing 30, 45, 60 and the idea was for him to play 60 or 70. But he had to play the whole match. He made the difference." On City's chances of claiming an unprecedented quadruple of trophies, Pellegrini added: "It's the same question the media asks every week. I don't know what will happen in the future. I'm absolutely sure if we play as we did in the first half, it is impossible. If we play as we did in the second half, maybe we can continue in all competitions. "We're not thinking about that. We've had a cup week, continued in the League Cup and taken another step in the FA Cup. Now, we have four games in the Premier League and will continue to try and win every game." Aguero's three well-taken goals were joined by a 25-yard shot from Aleksandar Kolarov, which squirmed past goalkeeper Jonathan Bond in the 87th minute to put City in front for the first time in the match. Earlier, City had looked in danger of the most unlikely of upsets when goals from Fernando Forestieri and Troy Deeney brought the visitors a deserved 2-0 half-time lead. "If I could change 11 players at half-time, I would have changed all of them," said Pellegrini. "It was more to do with attitude and intensity than the performance of individual players. The whole team didn't do things we normally do. But in the second half, we played with another tempo, another pace, and we continued to play the way we have the whole season at the Etihad. "We did not under-estimate Watford," the Chilean added. "But at half-time I was very worried. I told the players before the match that in the FA Cup, the Spanish Cup, the Italian Cup, everywhere, the team that plays from another division has a lot of motivation. I said if we didn't play with 100 per cent concentration and intensity, we wouldn't win the game. In the first 45 minutes we were jogging and, in that way, it was impossible to win." Source: FIFA.com