In recent experiments, we have for the first time measured near‐barrier and sub‐barrier transfer and/or breakup yields for an exotic Borromean nucleus6He, on a209Bi target. An isolated4He group was observed at an effectiveQ‐value of approximately −2.5 MeV whose integrated cross section was exceptionally large, greatly exceeding the fusion yield both above and below the barrier. Simultaneously measured elastic‐scattering angular distributions required total reaction cross sections that confirmed this large yield. Preliminary coupled‐channels calculations suggested that the reaction mechanism can best be described by direct breakup and neutron transfer to unbound states in211Bi. The calculations also predicted an enhancement in the sub‐barrier fusion yield due to coupling to the transfer and/or breakup channel, which strongly suggested that this is the doorway state that accounts for the remarkable suppression of the fusion barrier that was observed in a previous experiment. © 2003 American Institute of Physics