  To match the expected experimental precision at future linear colliders,
improved theoretical predictions beyond next-to-leading order are required. At
the anticipated energy scale of sqrt(s)=1 TeV the electroweak virtual
corrections are strongly enhanced by collinear-soft Sudakov logarithms of the
form log^2(s/M^2), with M being the generic mass scale of the W and Z bosons.
By choosing an appropriate gauge, we have developed a formalism to calculate
such corrections for arbitrary electroweak processes. As an example we consider
in this letter the process e^+e^- --> f fbar and study the perturbative
structure of the electroweak Sudakov logarithms by means of an explicit
two-loop calculation. In this way we investigate how the Standard Model, with
its mass gap between the photon and Z boson in the neutral sector, compares to
unbroken theories like QED and QCD. In contrast to what is known for unbroken
theories we find that the Sudakov logarithms are not exclusively given by the
so-called rainbow diagrams, owing to the mass gap and the charged-current
interactions. In spite of this, we nevertheless observe that the two-loop
corrections are consistent with an exponentiation of the one-loop corrections.
In this sense the Standard Model behaves like an unbroken theory at high
energies.
