If they just crash land on earth and charge at us heads on like bunch of brutes as shown in all these dumb ass alien invasion movies, then yes we may stand a chance, but since they're obviously more advanced than us why would they not use any advanced tactics at all? if they have super duper mega advanced space ships, why would they want to give us a fighting chance by engaging us in the atmosphere? they can just blast us from the orbit above.
In a more realistc invasion scenario, the aliens will gather information on us first, and design a perfect attack plan, they will not reveal themselves until they're ready to execute their plan. our satellites will be the first targets, once they're down we will fall into a world wide communication failure, in the confusion the alien invading force will cripple the countries that are powerful enough to pose threats to them. All political and military leaders of the USA, China and Russia will be disintegrated before they know what the fuck is going on, followed by the missile launchers and airports, the aliens will know precisely where they are according to their intel, once these are gone we're pretty much done for, conventional military is useless since they're attacking from the orbit. then they will systematically wipe out our defence and go on to enslave us or take our water or do whatever they want like using earth as their new holiday resort and keep us as sex slaves.
