Although it is certain that Chairon won another two victories apart from the four Olympian victories, it is unsure whether he won them at the Isthmia. This is entry 1/2 of these victories.
Farrington n. 685: 'Pausanias (Paus. 7. 27. 7) attributes to Chairon four Olympic victories and two victories in wrestling in another set of games, which, it was suggested by Boekh, who proposed ‘Ἰσθμικάς’ at 7.27.7, were the Isthmia, although most editors since then have preferred to leave the passage unamended.'