Location of the investigated sample of fast-rotating stars on the spectroscopic HR diagram with the non-rotating solar metallicity evolutionary tracks and ZAMS from Ekström et al. (2012; left). SB1 systems, runaway stars, and eclipsing binaries are labeled by different symbols in the same way as in Fig. 7. Gray dots represent the sample of slow rotating O-type stars (from Holgado et al. 2022). The same diagram but only showing the slow-rotating sample of O-type stars (right).