  Mid-rapidity azimuthal correlations probe di-jets originating mainly from
gluon-gluon hard-scattering. Measurements of such correlations have revealed
significant (gluon-)jet modification in central Au+Au collisions. Azimuthal
correlations of hadrons at forward rapidity with a mid-rapidity high-$\pt$
hadron, on the other hand, probe asymmetric partonic scatterings involving
large-x quarks and small-x gluons. We present preliminary results from STAR on
correlations of charged hadrons at forward rapidity in the forward TPCs
($2.7<|\eta|<3.9$, $\pt<2$ GeV/$c$) with high-$\pt$ charged hadrons at
mid-rapidity from the main TPC ($|\eta|<1$, $\pt>3$ GeV/$c$) in $pp$, d+Au, and
Au+Au collisions at $\snn=200$ GeV. The implications of the results for small-x
gluon distributions (Color Glass Condensate formation) and the energy loss of
quark jets at forward rapidity in nuclear medium are discussed. %Their
measurements in d+Au collisions, separately at the d-side and the Au-side, may
be sensitive to Color Glass Condensate in the Au-nucleus. Their measurements in
Au+Au collisions may probe quark-jet modification in nuclear medium.
