Question: Who is most respected for giving the man ranked as the sixth best active boxer one of the toughest fights of his career?
Sentence (from "Sergey Kovalev (boxer)"): "The Ring" magazine named him their Fighter of the Year in 2014, and in July 2016 he was ranked as the world's best light heavyweight by "The Ring" and BoxRec; both of which also ranked him as the world's third best active boxer, pound for pound.
Relevant evidence: No