Former Wimbledon champion Roger Federer was among the famous faces who joined fans thronging to see Bruce Springsteen.
The Swiss sporting legend was pictured at the event in Hyde Park on Thursday, as well as musicians Peter Gabriel and Billy Joel.
Springsteen, known as “The Boss”, rolled back the years during his three-hour set at British Summer Time (BST) – his debut performance at the festival.
Federer’s appearance at the London music festival follows his trip to Wimbledon earlier this week, his first time back since announcing his retirement last year.
He was welcomed into the Royal Box by the Princess of Wales as the pair watched his old rival Sir Andy Murray breeze into the second round.
Also pictured at Springsteen’s gig on Thursday was former Genesis singer Peter Gabriel.
Singer Billy Joel was also in attendance, ahead of his own performance at BST on Friday.
Springsteen called on London to “be good to yourself and the ones you love” as he rolled back the years during a three-hour, energy-fuelled set.
The US rocker, 73, ensured his BST debut would be a performance for the fans as he interacted with members of the 65,000-strong crowd and offered up hits from across his six-decade career.
US stars will close out the rest of the London festival with Springsteen returning for a second performance on Saturday and Lana Del Rey closing out the festival on Sunday.
