We show that the electric glueball becomes critical at the end-point of the
deconfinement phase transition in finite temperature QCD. Based on this
observation and existing lattice data, we argue that the chiral phase
transition at a zero quark mass and the deconfinement phase transition at an
infinite quark mass are continuously connected by the glueball-sigma mixing.Comment: 4 pages, terminology corrected. To appear in Phys. Rev.