  We report the discovery of an extremely close, eclipsing binary system. A
white dwarf is orbited by a core He-burning compact hot subdwarf star with a
period as short as $\simeq0.04987 {\rm d}$ making this system the most compact
hot subdwarf binary discovered so far. The subdwarf will start to transfer
helium-rich material on short timescales of less than $50 {\rm Myr}$. The
ignition of He-burning at the surface may trigger carbon-burning in the core
although the WD is less massive than the Chandrasekhar limit ($>0.74\,M_{\rm
\odot}$) making this binary a possible progenitor candidate for a supernova
type Ia event.
