AceShowbiz -

Jay-Z brought his Magna Carta World Tour to London's O2 Arena on Saturday night, October 12. At that night's show, the rapper gave his fans big surprise by bringing out two guests to perform a song with him.

The first guest was longtime collaborator Timbaland, who has been supporting Jay-Z on the European leg of the tour. The second one was pal Chris Martin, the lead vocalist of British band Coldplay. The three artists performed a tune called "Ain't No Love (Heart of the City)".

Prior to performing together, Jay-Z, Martin and Timbaland had already surprised their fans when they unexpectedly took the London underground known as Tube to reach the concert location. Along with a bodyguard, they were spotted at Waterloo station in Central London.

Some fans took to Twitter to share their excitement. "Seeing Jay Z on the tube getting mobbed arriving to O2!! #Buzzing Too starstruck to take a pic! #Jigga," a Twitter user said. Another user wrote, "Coming off the tube and I see Jay Z casually walking up the next escalator next to me... EVERYONE GOES NUTS!!"

Wearing a white T-shirt, black jacket and gold chains, Jay-Z was all smiles when he sat on the train. An eyewitness said that the rapper even had a conversation with a woman, who apparently had no idea who he was.