Same here, mate.
I´ve spent like an hour yesterday trying to beat a race on expert.
When I finally managed to stay in 1st the entire race, I mean, from start to one curve to finish, that motherf*** Knucles appear behind me out of thin air. And I was looking in the mini map and he was way back.
So this is it for me, I´ve done with this shit.
One thing is a game to be ridiculously hard, but a game that cheat is too much for me.
I´ll only get back to this crap after and If they make a patch to fix this difculty.