We study the mean-field phase diagram of glassy systems in a field pointing
in the direction of a metastable state. We find competition among a
``magnetized'' and a ``disordered'' phase, that are separated by a coexistence
line as in ordinary first order phase transitions. The coexistence line
terminates in a critical point, which in principle can be observed in numerical
simulations of glassy models.Comment: 4 pages, 5 figure
