Mika steals number one from Leona
It rose from third to number one while Just Jack's 'Starz In Their Eyes' moved from four to two. Lewis had spent four weeks in the top spot after winning a Christmas number one with 'A Moment Like This'.
The top 10 saw now new entries but singles from The View, Ordinary Boys and Jamie T were big risers.
In the album chart Amy Winehouse's Back to Black maintained the pole position while James Morrison held on at two with Undiscovered.
The top ten singles in full are:
1. (3) Mika: 'Grace Kelly'
2. (4) Just Jack: 'Starz In Their Eyes'
3. (11) View: 'Same Jeans'
4. (6) JoJo: 'Too Little Too Late'
5. (2) Eric Prydz Vs Floyd: 'Proper Education'
6. (1) Leona Lewis: 'A Moment Like This'
7. (22) Ordinary Boys: 'I Luv U'
8. (5) Take That: 'Patience'
9. (40) Jamie T: 'Calm Down Dearest'
10. (7) Booty Luv: 'Boogie 2nite'