Web monitoring firm Hitwise predicts Grand Theft Auto IV will outsell Halo 3 and become one of the biggest-selling video games in recent memory.

Pre-launch searches for 'Grand Theft Auto 4/IV' overtook those for 'Halo 3' by 22 percent, which historically equals greater sales, says Hitwise.

Further corroborating the findings is a new estimate by VG Chartz, which reports that Grand Theft Auto IV sold an impressive 4.2 million worldwide copies on Tuesday.