Reformed rockers Led Zeppelin have been forced to rearrange their hit songs for their upcoming reunion concert - after frontman Robert Plant struggled to hit high notes in rehearsals.

The legendary band, who will play their first gig in 19 years at London's O2 Arena on December 10, have recomposed the songs in a lower key because their aging vocalist's voice has deepened.

A source tells British newspaper The Sun, "He and guitarist Jimmy Page have had a few heated discussions about the upcoming gig. Jimmy is a bit rusty and Robert has been struggling with the high notes. To avoid any embarrassing vocal wobbles with the world watching, they decided it would be best to transpose the songs in a lower key."

(This news article provided by World Entertainment News Network)