THE Millennium Stadium tsunami relief concert is expected to sell out early this week after more than two-thirds of the tickets were snapped up in the first 24 hours.
More famous acts are expected to be confirmed for the January 22 line-up today.
Within hours of tickets becoming available on Saturday morning, phone lines were jammed and a queue of hundreds had formed outside the stadium.
About 20,000 tickets were bought in the first hour. By late on Saturday, half the 60,000 tickets had gone. Organisers said they had sold 40,000 by noon yesterday and by last night had sold almost 45,000 tickets.
Stadium manager Paul Sergeant said the response to the concert had been "fantastic" since it was announced on Friday night.
Fans have been told to buy tickets only over the phone because the stadium shop was inundated this weekend.
Stadium staff and the concert organisers met yesterday to plan the day-long event.
The concert's capacity was set at 65,000, but more tickets may yet be made available, Mr Sergeant said.
All proceeds from the concert, which it is hoped will raise at least £1m, will be donated to charities working in the Indian Ocean countries hit by the Boxing Day tsunami.
The disaster's death toll stands at more than 150,000, with about 50 Britons confirmed dead and a further 391 likely to have been killed. The Foreign Office says 2,000 Britons are still unaccounted for.
"We have sold just shy of 45,000 tickets. It was a fantastic achievement in the first 24 hours," Mr Sergeant said yesterday.
"We anticipated a bit of rush but probably not the rush we got.
"We did about half the tickets in the first hour. We anticipate selling out this week.
"When people get back to work on Monday, then we will start to see more interest in ticket sales."
Guitarist Eric Clapton heads the bill for the concert so far. Jools Holland, Katherine Jenkins, Aled Jones, Lemar and Feeder are also going to perform.
"It normally takes six months to do something like this and we are trying to do it all in a fortnight," Mr Sergeant said.
"It will put us on a world stage in the music industry - that we are a venue and a city that is capable of turning things around in a very short space of time."
It is understood Tom Jones had been invited to appear but was unable to come. "People can see on his website that he is playing Vegas and he is committed to that," Mr Sergeant said.
"Most people that are available or can make themselves available are being incredibly positive, but some simply are not available and that's fine."
Grant Nicholas, lead singer with Feeder, who were also involved in the Band Aid 20 single, said, "It was just really important for me to do it and I was adamant with our manager.
"I said I didn't care what we have got on, we just have to do it, so we have managed to somehow fit it in.
"People are interested but I'm not allowed to say who at the moment.
"All I'll say is there are other bands in our genre - really good bands in the frame."
The stadium wants to prevent touts from selling tickets for profit after some appeared on internet auction site eBay.
Mr Sergeant said, "It's appalling and if we can track down whoever has done this, they won't get them.
"It's disgraceful. They should be ashamed of themselves."
Tickets are available on 08705 582582, starting at £15