  The uncertainties in Parton Distribution Functions (PDFs) are the dominant
source of the systematic uncertainty in precision measurements of electroweak
parameters at hadron colliders (e.g. $\sin^2\theta_{eff}(M_Z)$,
$\sin^2\theta_{W}=1-M_W^2/M_Z^2$ and the mass of the W boson). We show that
measurements of the forward-backward charge asymmetry ($A_{FB}(M,y)$) of
Drell-Yan dilepton events produced at hadron colliders provide a new powerful
tool to reduce the PDF uncertainties in these measurements.
