Rumours from reliable sources may've ruined the surprise earlier today, but Sonsiphere Festival organisers have now officially confirmed that Iron Maiden and Rammstein will headline the 2010 event.
But contrary to former speculation, there is no Marilyn Manson or Fear Factory named in the first batch of acts, instead heavy metal fans are to be treated to exclusive festival performances from Alice Cooper and Anthrax.
There will also be a rare festival date from The Cult and the only UK festival shows in 2010 from Iggy And The Stooges and Slayer.
Festival chiefs have even gone one better by booking Motley Crue, who will make their Knebworth debut their only UK performance of the entire year.
Speaking about their headline show, Iron Maiden’s frontman Bruce Dickinson said: "Knebworth has been the home of so many legendary concerts going back many years it really will be a privilege to play there.
"We enjoy the camaraderie of playing great festivals and are very much looking forward to getting back out to do some shows next summer and, as it will be over two years since we played the UK, we will certainly be looking to deliver a memorable and spectacular night for our fans!"
Tickets for the festival have gone on sale today (Wednesday) at 6pm priced at £157.50 for a weekend camping ticket, with festival-goers able to secure their pass by paying a deposit of £40 and paying the remainder by 30 April 2010.
Click here to buy Sonisphere tickets.
The first 1,000 tickets paid for in full will come with a free pass to Sonisphere (Poland) 2010, which will feature performances from Metallica, Anthrax and more.
Sonisphere Festival 2010 will take place at Knebworth House from 30 July to 1 August.
The event was awarded the Best New Festival at this year’s UK Festival Awards and it extends to three-days for the first time in 2010.