Kaiser Chiefs played last year's festival
Thousands of Glastonbury Festival fans are jamming phone lines and its website after tickets went on sale earlier.
This year's event, which is being headlined by US rapper Jay-Z, takes place on organiser Michael Eavis's farm at Pilton, Somerset, from 27-29 June.
Fans had to register their interest in advance of tickets going on sale, with demand slightly down on last year.
Mr Eavis said 100,000 tickets had been sold on the first day - in past years all tickets had sold out in hours.
"I think three years of mud may have taken their toll, but even so, 100,000 isn't bad," he said.
Tickets went on sale at 0900 BST on Sunday morning.
Glastonbury spokesman John Shearlaw said the sale was "proceeding slowly but fairly".
"We have a total of 137,500 tickets on sale and there have been no problems reported back to us so far," he added.
"We have worked on the sales system extensively since last year and everyone has a fair chance."
He advised festival-goers to "be patient, keep trying and we will let you know when there aren't any tickets left".
Confirmed headliners also include Kings of Leon and The Verve, while Hot Chip and The Futureheads are also confirmed as playing.
The full line-up will be announced on 1 May.