Led Zeppelin fans are due to find out later whether their applications to see the band reunite on stage in London have been successful.
Led Zeppelin's tracks include Kashmir and Stairway to Heaven
More than a million people took part in an online ballot, but just 20,000 tickets are available for the show, on 26 November at the O2 arena in London.
The gig is a tribute to Ahmet Ertegun, the late founder of Atlantic Records.
Those who have been allocated tickets will be e-mailed by 0000 BST (2300 GMT) on Monday evening, a spokesman said.
Then they will have to pay £125 per ticket, plus booking fees.
Pete Townshend, Bill Wyman and Paolo Nutini will also perform at the concert.
Led Zeppelin's last full concert was in Berlin in July 1980, two months before the death of drummer John Bonham.
A show to celebrate the 40th anniversary of Atlantic Records in 1988 was the last time singer Robert Plant, guitarist Jimmy Page and bassist John Paul Jones all played together.
But a rift between Jones and the other two band members opened after Page and Plant started working together without him in the 1990s.
Proceeds from the show will go to an education fund set up in Mr Ertegun's memory.
The ballot is an absolute farce. I've lived, breathed and slept Led Zeppelin for the last 35 years. Joe Bloggs down the street has as much chance of getting a ticket as me, and he may only want to go because he likes Stairway to Heaven, and his selection is stopping genuine fans from going to this literally once-in-a-lifetime occasion for me.
Graeme Tomlinson, Workington, UK
I'd be interested to know how the organisers will be checking to see that ballot winners will be able to take up their tickets. I'm sure there will be many worldwide ballot entrants that would not be able to attend. Are those not able to get there just going to be selling their tickets on to touts?
John Reynolds, Cambridge, UK
The ballot idea was spot on, as otherwise ticket prices would have surely sky-rocketed. I sincerely hope they were also able to stop multiple entries and other abuses. Personally, although I had the opportunity to submit multiple applications through work, home and relatives' addresses, I chose to play fair and just submit one entry under my name.
Aaron Grech, Mgarr, Malta
If this is supposed to be a fair ballot, how on earth are companies advertising guaranteed standing seats online from £495 ex-VAT, ticket only, for £125 tickets? So much for organisers suggesting a fair ballot for fans. If you call these companies they are very vague about how they guarantee seats. The BBC should investigate whether the ballot is rigged, how many tickets are actually in the ballot and why there is already widespread touting for a charity concert.
Barry Nolan, Newcastle, UK
I wonder if all 20,000 tickets are in the lottery, or if all the industry insiders have had their dibs, and what's left is put in the draw. We all know how it works...
Mark, Weymouth, UK
They should switch it to Wembley (or similar) and give another 70,000 people the chance to see the best British band... ever! More money for the charity fund also!
Jonny Moore, London, UK
I think the ballot is a great idea. I did apply, but haven't heard anything yet. I think the organisers should go one step further and insist on a photo registration similar to Glastonbury. There are so many people from all over the world thinking they can cash in on selling the tickets on, and it's unfair on everybody.
Carrie Hall, London, UK
I applied. As successful applicants were meant to know by today and I've heard nothing, I guess I was not successful. Ballot was a good idea but would be better if they'd waited for next summer and played a bigger venue (with better sound). Don't know how well the ballot worked. No sign on the web, fan sites, blogs or eBay of anyone being allocated any yet. What is going to happen with any returns (eg. from overseas people who can't make the journey after all)?
Iain MacCall, London, UK
I suppose this seems the fairest way given the small number of tickets available but I bet the majority of tickets go to industry insiders as opposed to real fans. Still not heard anything yet be I'll be so gutted if I don't get to go. Led Zeppelin should take note of the fans' interest and do a tour.
Zeppelin Fan, Glasgow, UK
Don't be fooled by the hype. As soon as the tickets have gone at extortionate prices for this show, the band will announce a proper tour (you don't do all that preparation for one gig). The cash cow needs properly milking. Mark my words... a worldwide tour announced within a couple of weeks!
Mark, Wolverhampton, UK
The whole thing will be a massive disappointment which will damage the legend of Led Zep, as happened when the Sex Pistols reformed. If I attended the gig, I would be expecting Zeppelin circa Albert Hall 1970, but I have a sneaking suspicion they might not be "quite" as good as that.
Kim Brown, Harrogate, UK
As soon as the website opened I spent two days trying to register before I was succesful due to the website crashing. My wife and I haven't see Led Zeppelin since Knebworth in 1979 and we are desperate to see them. A bigger venue with possibly two gigs would have been a better idea for the true fans. If any tickets end up on eBay it will be a travesty and there should be a way of stopping the auction and cancelling those tickets as it is supposed to be for charity.
Geoff Bridges, Bedfordshire, UK
I still have my original ticket from when I went to see them in May 1975 at Earls Court. Of course, everyone producing such an original, thereby proving themselves to be genuine fans, should get a ticket for the reunion. Is this going to happen? Mmmm, I think not!
Kit Kitson, Melton Mowbray, UK
I applied for the lottery. I'm more than willing to catch a plane and hop the pond to see a once-in-a-lifetime show. I do agree that they should tour internationally as there is a large amount of new generation Led Zep fans that still appreciate the music of days gone by.
Jason Shepherd, Kelowna, Canada