"These ratings are quite extraordinary. It's something special and helps us understand why Take Two was so confident and adamant that they wanted to wait," UBS analyst Ben Schachter told Reuters news agency.
The game has been tipped to sell up to six million copies in a single week and Take Two is confident the final tally could be higher still.
"Our expectations are very high, higher than analysts give the game credit for," Take-Two chief executive Ben Feder told Reuters.
"All the analysts had a (sales) number, give or take, and I think we will be on the upside of that."
In May 1996, Rory Cellan-Jones took a tour of the office where the first version of Grand Theft Auto was being developed.
In the UK, 41 shops are understood to have put the game on sale at midnight, including outlets in Stevenage, Hertfordshire; Milton Keynes, Buckinghamshire; Hammersmith, in west London; and Bluewater Shopping Centre in Kent.
Reviews for Grand Theft Auto IV have been unanimous in their praise.
UK-based games website Eurogamer called it "game of the year" and handed it a 10 out of 10 review score, while the New York Times said it delivered a "new level of depth for an interactive entertainment experience".
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