City have led the Barclays Premier League for much of the season but were knocked off the top by Manchester United after defeat at Swansea on Sunday and they must overturn a 1-0 deficit as they meet Sporting Lisbon in the second leg of their Europa League last-16 tie at the Etihad Stadium on Thursday night.
De Jong said: "We always said at the beginning of the season we wanted to compete to win as many competitions as we can. We have come so far and we have just got to fight and concentrate until the end."
He added: "Our main goal is the Premier League, that doesn't change, but we're still in the Europa League and the only way we can succeed this season is to win one of the prizes.
"After we won the FA Cup, everybody is hungry for more.
"We brought players in to make the squad bigger and stronger. You can't have any excuses at the end of the day."
Yet despite the frustration of losing top spot, De Jong does not feel under extra pressure.
City trail by a point with 10 games remaining and De Jong thinks that gap is of little significance at this stage.
The 27-year-old said: "I don't think there is any advantage or disadvantage in which position you have in the league table if it is only one or two points.
"We just have to focus on what we do and United will do the same. For us as a team there is no pressure at all."
Source: PA
Source: PA