  The quark-connected and the quark-disconnected Wick contractions contributing
to the pion's scalar form factor are computed in the two and in the three
flavour chiral effective theory at next-to-leading order. While the
quark-disconnected contribution to the form factor itself turns out to be
power-counting suppressed its contribution to the scalar radius is of the same
order of magnitude as the one of the quark-connected contribution. This result
underlines that neglecting quark-disconnected contributions in simulations of
lattice QCD can cause significant systematic effects. The technique used to
derive these predictions can be applied to a large class of observables
relevant for QCD-phenomenology.
