London: Maverick Portuguese manager José Mourinho has termed his new assignment at English Premier League (EPL) giants Manchester United as a "challenge". The former Chelsea manager, who was presented on Tuesday in his new post, said he knew "what was expected" and added that he would take on the "challenge that comes at the right time with a lot of motivation". "I know what is expected of me. I know the history of the club and what the fans expect of me. I think this is a challenge that arrives at the right time in my career. I feel prepared and I have a lot of motivation," Mourinho told the media during his presentation. Mourinho also took a dig at his predecessor Louis van Gaal's football philosophy and said his only aim as Manchester United manager will be to win. Manchester United had a poor run under van Gaal last season. They finished fifth in the EPL, thus missing out on a spot in next season's Champions League. "It depends on the way you want to face it. I was never very good playing with words and hiding behind words and hiding behind philosophies. I was never good with that. I never tried to be. I was almost much more aggressive in my approach with the risks that can bring," Mourinho said. "It would be easy, honest and pragmatic from my side to focus on the last three years and focus on the fact that we don't qualify for the Champions League and so on. It would be pragmatic to say let's work and try to get back to the top four and do well in Europa League. I'm not good on that -- I don't want to be, I want to be more aggressive. And to be more aggressive is to say we want to win," the 53-year-old added. "I can anticipate that any of you that come with a question about the style of play and what is before is the result. I can imagine one of those questions is around the corner. I can anticipate by saying you can win a short competition, a couple of matches without playing well. But you can't win competitions by not playing well. What is playing well? To score more than your opponent; to make your fans proud because you win." Star forward Wayne Rooney has been struggling to recapture his best form in recent times both with his club and with the England team, but Mourinho insisted that the 30-year-old will still play an important part in Manchester United's campaign next season. "There are many jobs on the field. The most difficult to find is one to put the ball in the net. It is normal that a player at his age will change a little bit. One thing that will never change is his natural appetite to put the ball in the net. Maybe he is not a striker, not a No9 anymore. But with me he will never be a No6, playing 50m from goal," Mourinho said. "Yes, his passing is amazing but mine is also amazing without pressure. Many players have a great pass, but to put the ball in the net is the most difficult. He will be a No.9, a No.10, a No.9.5 but never a No.6 or a No.8."