The first four opening shows of the This Is It tour were postponed due to 'technical issues'. A clash with Madonna left no time for rehearsal at the O2 arena:
- 8 July 2009 -> 13 July 2009
- 10 July 2009 -> 1 March 2010
- 12 July 2009 -> 3 March 2010
- 14 Jully 2009 -> 6 March 2010
Source