utthāpanair unnayanaiś
cālanaiḥ sthāpanair api
parasparaṁ jigīṣantāv
apacakratur ātmanaḥ
utthāpanaiḥ - with lifting up; unnayanaiḥ - carrying; cālanaiḥ - pushing away; sthāpanaiḥ - holding stationary; api - also; parasparam - each other; jigīṣantau - wanting victory; apacakratuḥ - they harmed; ātmanaḥ - (even) themselves.
Śrīla Jīva Gosvāmī explains that although Kṛṣṇa and Balarāma did not, of course, harm Themselves, it appeared that way to Cāṇūra, Muṣṭika and others of mundane vision. In other words, the Lords were fully absorbed in the pastime of being wrestlers.