Over 500,000 Michael Jackson fans have so far signed up to see if they will get one of the 17,500 tickets for the memorial concert.
The show is set to be held at the Staples Center which is bases in Los Angeles on Tuesday. The singer died suddenly aged 50.
Fans who want tickets have been told to register with the Staples.com site where names will be drawn to see who get to attend.
Los Angeles Police are expecting a vast crowd with a possible 700,000 fans showing up at the venue but it will be off limits to anyone without a ticket.
Fans from anywhere in the world can apply for tickets. The concert is due to be held with a simulcast with the Nokia theatre which means 17,5000 fans will get to see the concert at no charge.
Anyone who gets a ticket will be informed on Sunday. Fans without tickets are being advised to watch the concert from home.
Los Angeles assistant police chief Earl Paysinger said:
"If you do not have a ticket, if you are not credentialed, not only will you not be allowed at these venues, you will not be allowed in this area,"
There have been some concerns about ticket touts and people applying for tickets to sell them on and there were some problems with the site which left fans from other countries such as the UK being unable to apply because the site would only accept a zip code.
These problems were quickly resolved but some of the practicalities haven't been. Fans from the UK, for instance, only notified on Sunday for a concert in the US on Tuesday are going to face an urgent scrabble to get a plane flight in time.