Retailer promotions saw sales of FIFA 09 rocket by 89 per cent according to the weekly sales data from Gfk-ChartTrack.
Call of Duty had been the UK's top selling games for the past five weeks.
FIFA 09 beat out Activision Blizzard's FPS, which has had to settle for second, and last minute potential chart topper Mario Kari Wii - at third - which was still sailing high in the charts despite being released over six months ago. (Of its 37 weeks on the market, Mario Kart has only been out of the top 10 for four weeks.)
Mario Kart, however, was only 3,000 unit sales behind Call of Duty, as sales were still up some 40 per cent. Call of Duty this past weekend saw a sales rise of 13 per cent.
EA also scored the fourth best selling game of the week - Need For Speed Undercover, which was also helped by retailer discounts - sales were up 27 per cent.
While neither Mario Kart or Nintendo's other contenders for the top spot like Wii Fit actually claimed the Christmas crown, Gfk-ChartTrack points out that this week's chart shows the Japanese firm in a great position; half the games in the top 10 were Nintendo published.
Brain Training is the only All Formats Top 10 title to drop sales - but it is down just one per cent and holds its place at number five.
Elsewhere, evergreen release Wii Play moves up one place to sixth while Wii Fit’ drops two places to tenth.
Plus the acclaimed but short-supplied Professor Layton and the Curious Village this week returned to the charts, at number eight, after last minute stocks were delivered to stores.
And Call of Duty aside, Activision Blizzard had another title in the top ten too, with price promotions pushing Bond tie-in Quantum of Solace back to the Top 10, up from No.13 to number seven.
The manic Christmas sales period also gave Eidos' Tomb Raider: Underworld a boost - the game rose one place to ninth in the top ten, with sales up 22 per cent.
The Gfk-ChartTrack top ten for the week ending December 20th is as follows:
1. FIFA 09
2. Call of Duty: World at War
3. Mario Kart Wii
4. Need For Speed Undercover
5. Dr Kawashima's Brain Training
6. Wii Play
7. Quantum of Solace
8. Professor Layton and the Curious Village
9. Tomb Raider Underworld
10. Wii Fit