Though only on shelves for a single day so far, Modern Warfare 2 is already shaking things up.  The title sold an amazing 1.23 million copies during it's opener in the UK, according to GFK-Chart Track numbers provided by MVC.  MCV projected last month that Modern Warfare  2 would sell 1.7 million copies opening week, and it appears to be well on the way to doing just that.

Of course, that sets the record for the best selling game in a 24 hour period in the UK, dethroning the 2008's Grand Theft Auto IV.  Rockstar's GTAIV did a respectable 600,000 copies in it's opener, but Modern Warfare 2 has more than doubled that up.

Sales were largely spurred by by the tremendously reduced price the game is going for in the UK.  Several big name retailers, including Amazon, slashed the price of the game to £26 - close to half off the suggested price - or less in order to stay competitive with other retailers.

No word on what the split was between the two platforms.