  We present a functional renormalization group calculation of the effect of
strong interactions on the shape of the Fermi surface of weakly coupled
metallic chains. In the regime where the bare interchain hopping is small, we
show that scattering processes involving large momentum transfers perpendicular
to the chains can completely destroy the warping of the true Fermi surface,
leading to a confined state where the renormalized interchain hopping vanishes
and a coherent motion perpendicular to the chains is impossible.
