Ground-based optical, magnetic and radar measurements detected a small substorm on October 9, 2000. Solar wind observations on GEOTAIL revealed a prolonged dominant Bz+ and steady By+ interplanetary magnetic field (IMF) prior to the substorm onset, except for a southward excursion at 0645--0655 UT, and a square-wave IMF Bx-By structure at 0727--0735 UT. We find that the IMF southward excursion led to the dayside convection enhancement and energy transport into the magnetosphere. When the dayside convection decreased, two pseudobreakups occurred as the consequence of the release of magnetospheric energy into the ionosphere. The substorm onset was associated with the IMF Bx-By structure in directly driven fashion. There was also a Stage-2 expansion which was internally driven within the magnetotail.