A 39-year-old man from Italy was also detained on suspicion of racially abusing a taxi driver.
Another man, from Anstey in Leicestershire, was questioned over a separate racially-aggravated offence.
Leicestershire Police said supporters from both clubs threw objects at each other towards the end of the game but there were no further arrests.
Napoli fans were kept at the stadium for a period after full-time as a precaution.
The force said all those arrested remained in custody and inquiries were ongoing.
The game finished 2-2 with the Italian side coming back from two goals down.