Initially Juventus dominated the match slightly and they managed to score a goal to get the win in the first half, but in the second half Napoli began to increase their attacking intensity and managed to equalize in the 57th minute. After that the match became more balanced as both teams attacked each other for a second goal, but because of a foul the referee awarded a penalty and Lukaku successfully scored to give Napoli the win in the match.
In football, what you got after a final whistle is important, and it's not important that how many minutes during the match, you dominated your opponent, made chances and impression. At the end of match, if you can not win it or worse if you lose it, it means you have a bad match. Any other excuse is only blaming your defeat to something else but you as a loser, is fully responsible for a loss.
This victory is very important for Napoli as they fight to stay in the Scudetto race this season with Inter Milan. This defeat made Juventus' unbeaten dominance begin to crumble because previously it was very difficult for any team to beat Juventus in Serie-A.
Napoli have another good match and 3 points to continue their Scudetto competition with Inter Milan. They still have to play many matches but if they can play well match by match, they will see a day of lifting Scudetto nearer and nearer. Napoli after more than a half of season, already shown their strength and they are competitive enough, ambitious enough to fight for Scudetto.