  An algorithm is presented, that provides a fast and robust reconstruction of
neutrino induced upward-going muons and a discrimination of these events from
downward-going atmospheric muon background in data collected by the ANTARES
neutrino telescope. The algorithm consists of a hit merging and hit selection
procedure followed by fitting steps for a track hypothesis and a point-like
light source. It is particularly well-suited for real time applications such as
online monitoring and fast triggering of optical follow-up observations for
multi-messenger studies. The performance of the algorithm is evaluated with
Monte Carlo simulations and various distributions are compared with that
obtained in ANTARES data.
