  We check the recently proposed higher loop Bethe-ansatz for the sl(2) sector
of N=4 at two loops by a direct perturbative calculation using N=2 superfields
in supersymmetric dimensional reduction. Our method can in principle address
operators built from many elementary fields and of arbitrary twist. We work out
in detail the spin three, twist three operator mixing problem at leading order
in N and find agreement with the prediction based on integrability.
