Log-log plot of the SFR vs. stellar mass. The black squares show our AzTEC SMG data points, while the red filled circles show the ALESS SMG data from da Cunha et al. (2015), where the ALESS sample was limited to sources with similar flux densities as our sample (see Sect. 4.2 for details). The dashed lines show the position of the star-forming main sequence at the median redshift of the analysed AzTEC SMGs (z = 2.85; black line) and the flux-limited ALESS sample (z = 3.12; red line) as given by Speagle et al. (2014); the lower and upper black dashed lines indicate a factor of three below and above the main sequence at z = 2.85.