  We discuss the extension of a systematic perturbative QCD based analysis to
the x -> 1 region. After subtracting a number of effects that transcend NLO
pQCD evolution, such as target mass corrections and large x resummation
effects, the remaining power corrections can be interpreted as dynamical higher
twists. The quantitative outcome of the analysis is dominated by the interplay
between the value of alpha_S in the infrared region and the higher twists. We
uncover a dual role played by alpha_S at large Bjorken x that can be used to
experimentally extract its value in the non-perturbative regime.
