  We investigate the phase structure of the $SU_f(2)\otimes SU_c(3)$
Nambu--Jona-Lasinio model as a function of the scalar diquark coupling
strength. Above a critical coupling, the binding energy is sufficiently large
to overcompensate the quark masses and a massless scalar diquark bound state
emerges which leads to Bose condensation already in the vacuum.
