  Metal-free stars are assumed to evolve at constant mass because of the very
low stellar winds. This leads to large CO-core mass at the end of the
evolution, so primordial stars with an initial mass between 25 and 85 Msol are
expected to end as direct black holes, the explosion energy being too weak to
remove the full envelope.
  We show that when rotation enters into play, some mass is lost because the
stars are prone to reach the critical velocity during the main sequence
evolution. Contrarily to what happens in the case of very low- but non
zero-metallicity stars, the enrichment of the envelope by rotational mixing is
very small and the total mass lost remains modest. The compactness of the
primordial stars lead to a very inefficient transport of the angular momentum
inside the star, so the profile of Omega(r) is close to Omega r^2 = const. As
the core contracts, the rotation rate increases, and the star ends its life
with a fast spinning core. Such a configuration has been shown to modify
substantially the dynamics of the explosion. Where one expected a weak
explosion or none at all, rotation might boost the explosion energy and drive a
robust supernova. This will have important consequences in the way primordial
stars enriched the early Universe.
