Hayseed Dixie will play the Bohemia tent at Sonisphere 2011 on the Friday night

THE opening riffs of this year’s Sonisphere 2011 rock festival will be heard in the grounds of Knebworth House tomorrow (Friday) afternoon.

Here the Welwyn Hatfield Times – the rock festival’s local paper – previews the Friday line-up.

Anthrax at Sonisphere Festival

JULY 8 will be ‘Big 4 Friday’ at Knebworth – a day metal fans attending Sonisphere 2011 thought they’d never see in this country.

It will be the first time thrash metal’s genre-defining foursome – Metallica, Slayer, Megadeth and Anthrax – have appeared on the same stage in the UK and fans can expect a mass jam during Metallica’s closing set.

“Having the Big 4 playing on the opening night is a huge coup,” said festival supremo Stuart Galbraith.

“They’ve never played in the UK together – to have them on the same stage is fantastic.

James Hetfield of Metallica

“Having the Big 4 is certainly something very special.”

As a legendary rock venue, Knebworth House has staged some of Britain’s biggest concerts over the past four decades.

The grounds of the gothic mansion staged Led Zeppelin’s seminal 1979 gigs – the last in this country with John Bonham on drums.

Seven years later, the Hertfordshire stately home hosted Queen’s final performance with flamboyant frontman Freddie Mercury in all his pomp.

Megadeth will play Sonisphere 2011 as part of the Big 4 on the main Apollo stage at Knebworth on Friday, July 8

In 1996, more than two million people applied for tickets to see Britpop giants Oasis perform over one mad weekend – a concert Galbraith was involved in.

And eight years ago, 375,000 fans crammed into Knebworth Park over three successive nights to see then former Take That member Robbie Williams entertain the masses.

For metalheads, the Big 4’s first-ever UK appearance will rank alongside those historic concerts.

Metallica – frontman and guitarist James Hetfield, drummer Lars Ulrich, long-time lead guitarist Kirk Hammett and bassist Robert Trujillo – headlined the inaugural Sonisphere at Knebworth in 2009.

Metallica on stage during their 2009 headline slot at Sonisphere. The thrash metal legends will return to Knebworth this year on Friday, July 8

Since then, promoters of the world’s largest international touring festival have sold more than one million Sonisphere tickets across Europe.

One of the reasons for that was the Big 4’s opening European dates last summer.

Now Britain gets the chance to experience the thrash legends together, all on the main Apollo stage, back to back.

Megadeth are the only one of the four metal titans to have not played the British leg of the international touring festival at Knebworth before.

Metallica on stage at the first Sonisphere Festival to be held in Knebworth

Main man Dave Mustaine, also a former member of Metallica, said: “I am glad to be part of this enormous celebration of thrash, speed and good old heavy metal.”

However, Anthrax co-founder and rhythm guitarist Scott Ian will not be playing at Knebworth this year.

His wife Pearl – the daughter of Meat Loaf – recently gave birth to the couple’s first child.

Taking his place will be Sepultura guitarist Andreas Kisser.

Scott Ian at an Anthrax press conference at Sonisphere Festival

Ian said: “We chose Andreas because we feel he can do the gig better than anyone.

“He has the fire, the attitude, and the crushing right hand to do the gig.”

Also missing Sonisphere’s UK leg will be Slayer axeman Jeff Hanneman.

The legendary guitarist contracted flesh-eating disease necrotizing fasciitis earlier this year.

Metallica will headline the Apollo Arena stage at Knebworth as part of the 2011 Sonisphere Festival on Friday, July 8

He was able to rejoin Slayer for the band’s final two tracks at the Big 4 concert in Indio, California, where the Coachella festival also takes place.

That epic first US Big 4 gig – there’s another planned for the Yankee Stadium in New York later in the year – gave metal fans a tantalising teaser of what to expect at Knebworth and dates in Germany and Sweden last week have further raised expectations.

Joining the Big 4 on the main Apollo stage tomorrow (Friday) as special guests will be British heavy metal group Diamond Head, one of Metallica’s biggest influences.

They will open proceedings around 3.15pm – and one of their tracks, possibly Am I Evil?, is likely to feature in the Big 4 jam at the end of the night.

And if that wasn’t enough for festival-goers, post-punk industrial rockers Killing Joke, featuring the band’s original line-up, will provide the late-night after-Apollo show entertainment in the Bohemia tent.

Then bluegrass rock covers band Hayseed Dixie will perform in the early hours.