Vampire Weekend opened Glastonbury's second day with a secret show on the Park Stage.
The band played covers of Fleetwood Mac's Everywhere and Chicago's Summer In The Park, alongside their own hits.
The laid-back set even included audience requests - with the band performing tracks like Cape Cod Kwassa Kwassa and Giant as a result.
Other acts on Saturday's line-up include The Killers and Janet Jackson.
Temperatures at the festival have hit 31C, and queues are building at water refill points, while showers were turned off in some areas to conserve supplies.
Earlier in the day, rumours spread that the site was experiencing a water shortage, but organisers assured festival-goers that "the supply is running as normal".
The heat became a focal point for performers around the site.
"Yo, Glasto! How you feeling?" shouted pop singer Anne-Marie as she played the Pyramid Stage in the early afternoon. "You're all getting a tan. You're all going to be very brown."
After Stormzy's headline set on Friday, Scottish troubadours The Proclaimers were the first act out on the Pyramid Stage, triggering a mass singalong to hits like (I'm Gonna Be) 500 Miles and I'm On My Way.
"It was blimmin' hot out there," singer Charlie Reid told the BBC, "and I imagine it's going to get hotter and hotter as each band comes on".
Stewards are passing out free water and sun cream to festival-goers at the front of the crowd, to combat dehydration and sunburn.
"I was really nervous about today, I actually had a nosebleed last night," confessed pop star Anne-Marie, as she surveyed the thousands of fans who'd turned up to see her play hits like Friends, 2002 and Rockabye.
"If it starts again, can someone warn me, 'cos I'm wearing a white dress?"
Meanwhile, Johnny Marr told the BBC the hot weather could be his fault.
"I've played here five times. I first came in 1984 with the Smiths, then with Modest Mouse and The Cribs, and finally with my own band, and every time I've been here, it's been sunshine," he laughed.
"Am I Glastonbury's good luck charm? Well, obviously."
The star brings his third solo album, Call The Comet, to the Other Stage later this evening.
"I don't like playing in sunglasses," he said, "but it might have to be a thing."