  We present observations of Sakurai's Object obtained at 1-5um between 2003
and 2007. By fitting a radiative transfer model to an echelle spectrum of CO
fundamental absorption features around 4.7um, we determine the excitation
conditions in the line-forming region. We find 12C/13C~3.5, consistent with CO
originating in ejecta processed by the very late thermal pulse, rather than in
the pre-existing planetary nebula. We demonstrate the existence of
2.2e-6<M<2.7e-6 Msun of CO ejecta outside the dust, forming a high-velocity
wind of 500+/-80 km/s. We find evidence for significant weakening of the CO
band and cooling of the dust around the central star between 2003 and 2005. The
gas and dust temperatures are implausibly high for stellar radiation to be the
sole contributor.
