Sorry Koopa but 1m in 1st week is impossible. Only an established popular franchise could have any reasonable expectations of doing that.
Killzone 2 couldn't even pull in 1m in 1st week and that had massive hype.
CoDWaW just reached 1m on Wii after months despite being the best online FPS on the system and a massive brand.
No More Heroes - the closest comparible to MadWorld couldn't even muster 400k lifetime.
If MadWorld ever passes 1m sales then that'll be a huge success for Sega and Platinum Games. But I doubt even that will happen.