  We discuss New Physics effects in fermion pair production at LC in the
framework of the ``Z-peak subtracted approach'', a theoretical scheme that
exploits the experimental measurements at LEP1 and SLC as input parameters. In
particular, we discuss the role of the longitudinal polarization asymmetry
$A_{LR,\mu}$ which turns out to be a very sensitive probe to New Physics of
universal type. The extension of the method to non universal effects is
discussed and an application is given in two examples: general contact
interactions and low energy gravity models with graviton exchange.
