transform.position in fixedUpdate() different from transform.position in Update();

I have been trying for some time to do a raycast from fixedUpdate() that is supposed to originate from the center of the sphere in the downwards direction. Problem is that at the higher speeds (10+) raycast does not happen from the sphere's transform.position but rather lags behind to the extent where the ray isn't even in the object itself anymore but a lenght or two behind and the distance increases with speed. There is no such problem in the update() as the transfrom.position in Update() is correct even under high speeds.

Pseudo-code:

fixedUpdate(): position = transform.position; ray(origin = position, direction = -transform.up);