Srimad Bhagavatam Canto 10, Chapter 44, Text 05

SB 10.44.5

utthapanair unnayanais
 calanaih sthapanair api
parasparam jigisantav
 apacakratur atmanah
 
Translation: 
 
Forcefully lifting and carrying each other, pushing each other away and holding each other down, the fighters hurt even their own bodies in their great eagerness for victory.
 
Purport: 
 
Srila Jiva Gosvami explains that although Krsna and Balarama did not, of course, harm Themselves, it appeared that way to Canura, Mustika and others of mundane vision. In other words, the Lords were fully absorbed in the pastime of being wrestlers.
Srimad Bhagavatam Canto 10, Chapter 44, Text 04
Srimad Bhagavatam Canto 10, Chapter 44, Text 06