Kylie Minogue has said she is "so sorry" that a major outdoor concert has been axed, which would have seen her reunited on stage with Jason Donovan.
The Hit Factory show, celebrating the music of Pete Waterman, was cancelled with just hours to go because of safety fears due to heavy rainfall and mud in London's Hyde Park.
Kylie was set to join former Neighbours co-star Jason on stage for the first time in more than 20 years at the gig, for a performance of their chart-topping hit Especially For You.
Promoters spent hours trying to get the site into a fit state after the ground was churned up by downpours and visitors at last weekend's Wireless concerts. But site was declared "unfit" this morning.
"The potential risk to staff and music fans was too great for the event to go ahead," organisers said.
The show was due to feature many of the acts producer Waterman had catapulted to fame through his PWL record label - which celebrates its 25th anniversary this year.
Kylie said: "I am so sorry to hear that the concert tomorrow had to be cancelled. I feel for all the fans who had bought tickets to this special event.
"Jason and I were rehearsed and excited to share this moment with everyone."
Promoter Live Nation and The Royal Parks, which operates the site, said they "sincerely regret the disappointment caused by this cancellation".
Fans are being advised to seek refunds from the place they bought tickets, although those who purchased through Ticketmaster and See Tickets are being promised automatic refunds.