[Q] Need Help in flashing rom in a phone which does not have ext memory card topic

Hello Guys, i have micromax canvas knight phone which does not have external memory card support. The phone is rooted and i need to flash a rom. For that i need to wipe data/factory reset, as i put the rom zip file in internal memory, rom file would get erased. Since factory reset is mandatory before flashing a new rom through recovery, how can we do that without losing the rom file in internal memory? Please help.