Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
champion [ˈtʃæmpɪən] n (SPORT) чемпио́н; (of cause) побо́рник[-ица] (of person) защи́тник[-ица]
vt защища́ть (защити́ть*perf)
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.
Русский: