By Daily Mail Reporter
New bandmate: Black Eyed Peas welcome their new member Tom Cruise as they perform onstage at London's O2 Arena
When the Black Eyed Peas spotted an intruder onstage, they could have been excused for calling security.
But it was none other than movie star Tom Cruise, who had been secretly asked to join the band for their final song by singer Fergie.
The actor stunned fans - and Fergie's bandmates - when he took the stage at the band's London show at the O2 arena and even helped them perform their final song.
Peas' star will.i.am admitted: 'Even we were surprised - Fergie was the only one who knew about it.'
Rocking out: Tom and Fergie belt out I've Got A Feeling
But Cruise said he felt in no position to not hit the stage, after being encouraged by Fergie.
'Fergie gave me a formal invitation to come onstage,' Cruise said.
'The way she said it was, "Don't be a wuss, you've got to come on stage for the last song".'
Will.i.am said: 'He rocked out to I've Got A Feeling. The crowd loved it.'
Having a blast: Tom stole the show during the band's finale
New friends: Tom and wife Katie Holmes pose with singer Fergie
Cruise has grown close to the band after working with them on the soundtrack of his new movie Knight And Day.
'I met Will at a charity event and we said we've got to work together,' Tom recalled.
'Then afterwards we went to see the Peas over the Super Bowl weekend and afterwards we met up again.
Surprise duet: Tom Cruise and will.i.am on stage at the aftershow party last night; Tom had earlier joined the Black Eyed Peas at the O2 Arena
Working together: Will and Tom on Good Morning America today
'We were about three quarters of the way through shooting Knight And Day and I just thought, "We've got to have the Black Eyed Peas do a song. It's a perfect match."
'So Will came by the editing room and we showed him some scenes - and he just started writing the song there in the room.
'We were amazed - it was pretty incredible.'
Will.i.am said: 'I'm a fan of Tom's and I was so thrilled when they asked me to collaborate.'
Crowd pleaser: Fergie, Taboo and will.i.am during their set; Cruise joined them for the show
Furry lady: Fergie leaves St Martin's Lane Hotel wearing a Henry Holland coat in London yesterday