There was a new entry at number two for Eric Prydz Vs Floyd with 'Proper Education', while last week's second placed record, 'Patience' by Take That, drops one place to three.
Another new entry in the top ten comes from U2, whose single 'Window In The Skies' debuts at four, while Snow Patrol take advantage of the new chart rules, re-entering the top 40 at number 9, with 'Chasing Cars'.
The new regulations mean songs no longer have to be physically sold to make them eligible for chart status, giving re-entry to a number of songs including Gnarls Berkley's 'Crazy' (No. 30) and The Automatic's 'Monster' (33).
Take That continue their dominance of the album charts, with "Beautiful World" rooted to the top spot for the sixth week running.
The top ten singles in full are:
1. (1) Leona Lewis: 'A Moment Like This'
2. (-) Eric Prydz Vs Floyd: 'Proper Education'
3. (2) Take That: 'Patience'
4. (-) U2: 'Window In The Skies'
5. (4) Akon Ft Eminem: 'Smack That'
6. (6) Booty Luv: 'Boogie 2nite'
7. (5) Cascada: Truly Madly Deeply
8. (8) Sharam: 'Patt (Party All The Time)'
9. (re) Snow Patrol: 'Chasing Cars'
10. (23) Chris Cornell: 'You Know My Name'