  We study the forward-backward asymmetry $A_{FB}$ in $pp \to \ell^+\ell^-$ at
the Z peak within the Standard Model Effective Field Theory (SMEFT). We find
that this observable provides per mille level constraints on the vertex
corrections of the Z boson to quarks,which close a flat direction in the
electroweak precision SMEFT fit. Moreover, we show that current $A_{FB}$ data
is precise enough so that its inclusion in the fit improves significantly LEP
bounds even in simple New Physics setups. This demonstrates that the LHC can
compete with and complement LEP when it comes to precision measurements of the
Z boson properties
