Radiohead star Colin Greenwood is taking part in a gruelling triathlon in honour of a friend's daughter who is battling leukaemia. The British rocker will tackle running, cycling and swimming during the race in his native Oxfordshire, England in June (14). Greenwood is raising money for a charity called Scarlett's Dragons and admits the cause is close to his heart. In a post on his Twitter.com page, he writes, "In a moment of madness I've agreed to enter a triathlon for my mate Dan's daughter Scarlett - www.scarlettsdragons.co.uk Sponsor me! x Colin." He later adds, "Just got back from 10k (kilometre) stagger around the park - amazed by your kindness and support already! Go Scarlett!!" The Leukaemia & Lymphoma Research Blenheim Palace Triathlon takes place over two days on 7-8 June (14). Greenwood and his charity team had raised more than $21,085 (£13,178) as WENN went to press.