Antonio Conte's Inter ended their 23-year wait for a league win in Naples to stay in pole position, level on points with Juventus after 18 games, but ahead on goal difference.
Lukaku scored a brace last weekend against Sassuolo to keep Inter second in Serie A, one point behind defending champions Juventus, after eight games.
Romelu Lukaku scored two goals in the match and Belgium registered a massive 9-0 victory in the match.
The Belgians were criticised by coach Roberto Martinez for starting slowly against Panama in their first group match but flew out of the blocks in Moscow.
During an interview, Eden Hazzard said that Romelu Lukaku had been hiding in the first half against Panama.
Belgium just needed a spark from somewhere, and they got it from Dries Mertens in the 47th minute.
With Zlatan Ibrahimovic fit again and closely scrutinising his performances from the substitutes' bench, Lukaku is under pressure to rediscover his goal-scoring touch.
A lawyer for Lukaku, who was not required to be in court in Los Angeles, entered the plea on the player's behalf during a brief hearing before commissioner Jane Godfrey.
Lukaku scored twice in the first half off crosses from Anthony Martial, while Martial got his name on the scoresheet with a penalty.
The Belgium striker has scored six goals in six games for United so far, including the debut one against Real Madrid in UEFA Super Cup.