Coldplay perform with Keys in Japan

Coldplay performed with Alicia Keys at the Summer Sonic festival in Japan on Sunday.

The American R&B singer played piano on the indie band's hit single 'Clocks' during their headline set.

Frontman Chris Martin introduced Keys as "the most beautiful woman in the world... except for my wife".

Earlier, Martin changed the lyrics to the album track 'Politik', singing: "60,000 Japanese people watching us, let Alicia Keys always play with us."

The singer also adapted the group's 2005 number two single Speed Of Sound, incorporating samples of Japanese pop group SMAP.