Q-band EPR spectra of CS2Cu(ZrF6)(2). 6H(2)O measured in temperature range 4.2-350 K and supported by the X-ray crystal structure analysis, show a gradual transformation of an adiabatic potential surface of the Jahn-Teller (JT) Cu(H2O)(6)(2+) complex leading to the switch of its elongation direction. This effect is joined with a ferroelastic phase transition at 320 K. It is shown that gradual movement of minima of the adiabatic potential surface along the phi coordinate for rho congruent to rho (0), describing this phenomenon, is a result of a competition between a small lattice deformation at T > T-c and the new deformation appearing at T-c and increasing with decreasing temperature.