Retail analysts Chart-Track have revealed 926,000 copies of GTA IV were sold in the UK during the game's first five days on sale.
514,000 of those were for Xbox 360, with the remaining 413,000 for PS3 - a split of 55 per cent to 45 per cent.
On day one alone, 631,000 copies of the game were sold. According to Chart-Track, GTA IV software revenue is bigger than the revenue of all other games during any week this year since the first seven days of 2008.
What's more, in its first week GTA IV sold more copies than all but the top three best-selling games of 2007 (FIFA '08, Brain Training and Call of Duty 4).
The title also boosted hardware sales - PS3 by 127 per cent over the previous week, and Xbox 360 by 125 per cent.
GTA IV has beaten predecessor Grand Theft Auto: San Andreas in the record-breaking stakes. That game, which launched on 29th October 2004, sold 501,000 copies on its first day and 677,000 in its first week - which consisisted of two days, due to the day of the week it was released. At that time, the PS2 had an installed base of around 6.6 million.
Now GTA IV is the new record holder for all-formats - but San Andreas still holds the day one and week one records for the individual format.