Hosts Napoli, who moved level on points with Juventus in third, went close through former Palermo striker Edinson Cavani and finally made the breakthrough when the Uruguayan set up Maggio for almost the last kick of the match.
The game was billed as a battle of the South Americans between Cavani and Palermo team-mate Javier Pastore and his fellow Argentine Ezequiel Lavezzi of Napoli, who went off injured, but in the end an Italian settled matters.
Serie A players are due to strike this weekend in a dispute with the league over a new collective contract, with the union refusing to agree to plans to force unwanted footballers to train away from the first team squad or accept a transfer.
The soccer federation holds the latest in a series of talks on Tuesday in a bid to stop the unpopular strike, which several players have said is not a good idea given Italy's economic plight and the large wages footballers receive.
Media and angry fans have also said the industrial action would be an own goal for the players' union, who have left the door open for a possible late compromise.
Among highlights from this weekend's action, AC Milan stayed three points clear at the top by beating Brescia 3-0 on Saturday.
