Let's stop for a moment just to admire how much Đoković has grown in languages, also conpared to the big 3.
Nadal - native Spanish, barely got his English to passable, never went to any other length or attempted to learn anything else.
Federer - native Swiss German, picked up flawless German from young age, learned flawless English, picked up okayish-good French in high school years (when he was forced to, as his parents sent him to a French speaking school). However, after high school, he didn't bother learning any other language.
Đoković - native Serbian, learned flawless English, excellent Italian, good German, passable French, passable Spanish, still learning languages even in his 30s.
In terms of effort and breadth, Đoković is also the multilingualism GOAT.
Nadal - native Spanish, barely got his English to passable, never went to any other length or attempted to learn anything else.
Federer - native Swiss German, picked up flawless German from young age, learned flawless English, picked up okayish-good French in high school years (when he was forced to, as his parents sent him to a French speaking school). However, after high school, he didn't bother learning any other language.
Đoković - native Serbian, learned flawless English, excellent Italian, good German, passable French, passable Spanish, still learning languages even in his 30s.
In terms of effort and breadth, Đoković is also the multilingualism GOAT.