Top: phase lag between the V- and the J-band light-curve of SMC Cepheids. The black open circles are estimated by adopting the epoch of maximum brightness as phase zero-point, while the orange dots by adopting the new phasing, i.e. the epoch of the mean-magnitude along the rising branch. The red lines show the linear fit of the orange data set. The rms (dashed lines) are also overplotted. The values of the medians and of the rms are labeled in the top of the panel. Middle: same as the top, but for the H band. Bottom: same as the top, but for the K_S band.