By Ian Youngs
Music reporter, BBC News, at the Glastonbury Festival
Scissor Sisters singer Jake Shears co-wrote a song on Kylie's new album
Kylie Minogue has made her Glastonbury Festival debut as a guest with Scissor Sisters on the main Pyramid Stage.
The pop star was due to headline the event in 2005 but pulled out when she was diagnosed with breast cancer.
Kylie appeared for one song as a surprise guest to help celebrate the festival's 40th anniversary.
Another unexpected star appeared later, when U2 guitarist The Edge played with headliners Muse. U2 had been due to play but were forced to pull out.
Festivalgoers have been enjoying blazing sunshine rather than the customary rain and mud.
More than 2,100 people have been treated by the festival medical team - many for dehydration and sunburn.
Two people died after suffering heart attacks on site on Friday night.
On stage, Kylie joined Scissor Sisters to sing Any Which Way, a track from the group's new album Night Work.
"We heard a rumour on the radio," said one fan, Scott Rees, 27, from Pontypool, Wales.
"It's nice to see her on the stage because she was supposed to play a few years ago. I thought it was good for the anniversary."
Alan Miles, 23, from Southampton, said: "I was very surprised because I was completely not expecting it.
"You hear a few rumours but I didn't bother listening. Kylie turned up and the crowd went mad. It was absolutely brilliant.
"It's one of those festivals that just caters for every kind of music.
Those attending the festival have swapped wellies for flip-flops
Scissor Sisters singer Jake Shears co-wrote a song on Kylie's new album and said they helped each other out when they were struggling with their new records.
"This is a really special time for both of us," he told BBC Radio 1's Natalie Jamieson.
"She came and visited me when I was in Berlin a year ago and we were both in a similar spot. We both didn't know what we were going to make for records.
"We both felt a little bit lost in a way and having a similar parallel journey this past year has been really special."
Stadium rockers Muse followed Scissor Sisters on the Pyramid Stage and The Edge came out with the band for their encore.
Their version of Where The Streets Have No Name provided a memorable Glastonbury moment.
The Edge's appearance went some way to making up for U2's absence, due to Bono needing emergency spinal surgery.
Other acts on the bill on Saturday included Shakira, The Pet Shop Boys, The xx and Laura Marling.
Meanwhile, festival organiser Michael Eavis, who started the event on his Somerset dairy farm, appeared on the Acoustic Stage on Saturday for his first slot in the festival's history.
Mr Eavis, now 74, was interviewed by BBC Radio 2 DJ Johnnie Walker about building up the world's largest greenfield festival over the last four decades.
He revealed that the festival's future was in jeopardy in 2008, when tickets did not sell out until the event was under way.
"I was frantic about going bankrupt," he said. "We haven't got any reserves, you see. I lost a stone of weight - I got really frantic that year."
He said he was also worried about the festival being scuppered by problems such as foot-and-mouth disease, bird flu or water shortages.
"It hasn't stopped us so far, and hopefully never will," he told fans.
He also discussed beating stomach cancer 15 years ago and was asked whether he was planning to retire and hand over the festival to daughter Emily.
"I'm not feeling like packing it in at the moment," he replied.
Listen to continuous Glastonbury coverage on BBC 6 Music and watch performances on BBC Two, BBC Three and BBC Four.