  We present results from a numerical study of spherically-symmetric collapse
of a self-gravitating, SU(2) gauge field. Two distinct critical solutions are
observed at the threshold of black hole formation. In one case the critical
solution is discretely self-similar and black holes of arbitrarily small mass
can form. However, in the other instance the critical solution is the n=1
static Bartnik-Mckinnon sphaleron, and black hole formation turns on at finite
mass. The transition between these two scenarios is characterized by the
superposition of both types of critical behaviour.
