Subject of the 3rd and 4th Isthmian Odes of Pindarus. Melissos won the pankration (Pi. I. 4.2-3, 44) at the Isthmia; in Pi. 3.9-13 an unspecified victory at the Isthmia is recounted, as well as some equestrian victory at Nemea - the Loeb edition translates 'hippodromia' as chariot racing, and implies the unspecified victory at the Isthmia were in the same category (reasonable, given the rest of the poem records Melissos' ancestors fame with chariots). Farrington however, reasoning that the 3rd Ode is chronologically later than the 4th, argues that the unnamed Isthmian victory is actually the same as the victory in the pankration from the 4th ode; it is a complex discussion, for which I refer to Farrington (2012), p. 111-2 note 239. We follow Farrington. Pi. I. 4.65-71 also mention 3 victories, of which one as a pais, at some annual festival, presumably the Theban Iolaea (according to the scholiasts).
For the dating I follow Farrington (2012), no. 1.33 and p. 111-2 note 239, based on the dating of both poems. - PK