Gas fraction μ_mol(left panel) and depletion timescale (right panel) plotted versus the sSFR-excess for the same samples and with the same colour code presented in Fig. 3. The values for XID2028 are slightly offset in the x-axis for clarity. All quantities are normalized to the expected values for normal and Starburst galaxies predicted by the calibration presented in Sargent et al. (2014). The black line traces the expected variation (median) with sSFR for a MS spiral galaxy with identical mass and redshift as XID2028 (see Sargent et al. 2014). The step at sSFR/ ⟨ sSFR ⟩ ~ 4 reflects the transition from the main sequence locus to the sSFR-regime where high-SFE Starbursts dominate. XID2028 lies a factor ~2 to ~10 below the black line. I.e. it shows significant lower gas fraction and depletion timescale than those expected for the properties of its host galaxy.