Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
uncontested [ʌnkənˈtɛstɪd] adj (champion) неоспори́мый/неоспори́м
uncontested election вы́боры, на кото́рых баллоти́руется (лишь) оди́н кандида́т
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.