EA and Valve's Portal 2 has held firm at the top of the All Formats All Prices UK video game chart, despite a 51 per cent drop in sales over its first week.

Mortal Kombat also sticks at No.2, while Zumba Fitness climbs one place to No.3 and Operation Flashpoint: Red River blasts its way upwards to No.4. Kinect Sports was a major mover up from No.31 to No.17.

The week's only new entry is SEGA's Virtua Tennis 4 at No.23, no doubt set for a sales surge when the pros don their whites for Wimbledon. SEGA's Thor video game couldn't build on the strong word of mouth about the movie, failing to even make the Top 40.

Leisure software charts compiled by Chart Track, (C)2011 UKIE Ltd (All Prices) Week 17, 2011

1. PORTAL 2

2. MORTAL KOMBAT

3. ZUMBA FITNESS

4. OPERATION FLASHPOINT: RED RIVER

5. CALL OF DUTY: BLACK OPS

6. LEGO STAR WARS III: THE CLONE WARS

7. FIFA 11

8. WII FIT PLUS

9. HOMEFRONT

10. JUST DANCE 2

11. CRYSIS 2

12. POKEMON BLACK VERSION

13. MICHAEL JACKSON: THE EXPERIENCE

14. POKEMON WHITE VERSION

15. TIGER WOODS PGA TOUR 12: THE MASTERS

16. WII SPORTS RESORT

17. KINECT SPORTS

18. DRAGON AGE II

19. ASSASSIN'S CREED: BROTHERHOOD

20. LEGO HARRY POTTER: YEARS 1-4

Next week sees the release of Sniper: Ghost Warrior on PS3. The game was a surprise hit on Xbox 360, but will the City Interactive shooter deliver a repeat performance? Also new is Nintendo's Steel Diver for 3DS, which while looking like decent fun isn't likely to chart too high.

We expect Portal 2 and MK to continue their run at the top, with competition from Black Ops on the back of increased marketing thanks to the Escalation map pack.