Assuming the ftg tag is off of obito in this fight, he will get hit only if he is trying to warp. obito can also use izanagi for ten minutes so minato won't defeat him until time is up. Also, obito won't be dumb enough to take on a stronger version of minato when he can't take him in base, since that's the case, he will be alongside nagato to help him phase minato attack.