The 62-year-old has worked in the Eredivisie, the Bundesliga and and La Liga – managing Ajax, Bayern Munich and Barcelona respectively – but insists that Manchester United are the biggest club in the world because of their global reach.“This is the biggest club I've managed because of its worldwide renown. But every season you have to prove you are the biggest club,” Van Gaal told a news conference.“I have managed Ajax, the number one club in Holland. I have managed Bayern Muenchen, the biggest club in Germany. And I have managed Barcelona, in my opinion, the biggest club in Spain."Manchester United finished seventh last season, but I hope we can be the biggest club in England this year.”Van Gaal said he believes he can meet the expectations for success at "the biggest club in the world" but refused to indulge in predictions.The Dutchman, smiling and looking relaxed after arriving from his stint as Netherlands manager at the World Cup, also made it clear that the commercial demands at United would make his job harder."I'm now two days here. I've met a lot of people, and when you see that kind of people loving the club they expect a lot of me."Can I fulfil that expectation? I think I can, but because of the greatness of this club it is much more difficult than in another club."This club is also guided in a commercial way and we have to fulfil that also, but it is not always possible to fulfil both."I will do my utmost best. That's what I can give. I cannot give predictions."Van Gaal added: "I cannot give predictions because you never know. It's the biggest club in the world. Within two days I know already how important Manchester United is but also how important the sponsors are."I have to adapt to this big club. It will not be easy but you can see what I have won."When asked about not taking a holiday following the World Cup, Van Gaal said he could not think about having a vacation with such a huge challenge hanging over him."I could not let them go. When you are asked by the biggest club in the world, it's a big chance for me," he said."When there is a challenge like this, I never let it go."At the start of the press conference he addressed how much of an honour it was to have United hero Sir Bobby Charlton introducing him to the club during this period."I want to thank Sir Bobby Charlton because it's a great honour to come in this stadium and to be guided by him. My first steps - okay my first steps here were with Bayern Munich and Barcelona, I know that - but as the coach of Manchester United these were my first steps. I was very proud to do that with Sir Bobby Charlton."(uk.eurosport.yahoo.com)Bakudaily.az