We investigate the in-medium modification of the charmonium breakup processes
due to the Mott-effect for D-mesons at the chiral phase transition. A model
calculation for the process J/Psi+pi --> D+D^*+ h.c. is presented which
demonstrates that threshold effects in the thermal averaged breakup cross
section can be explained as a Mott transition where final state quark-antiquark
bound states enter the continuum of resonant states at the QCD phase
transition. Applications to heavy-ion collisions within a modified Glauber
model scenario and the phenomenon of anomalous J/ψ suppression in the CERN
NA50 experiment are addressed.Comment: 5 pages, 4 figures, uses JHEP.cls styl