Hunting a first league title since 1990 when Diego Maradona was still strutting his stuff in Naples, Napoli are six points ahead of third-placed Inter after a third straight win which came without suspended star striker Victor Osimhen.
They prevailed in Bergamo thanks to Lorenzo Insigne's early penalty, a sweet Matteo Politano volley eight minutes before halftime and a stunning late breakaway finished by Eljif Elmas just as Atalanta were pushing for a leveller after Marten De Roon pulled one back in the 59th minute.
Luciano Spalletti's side sit side-by-side on 66 points with Milan, who host Bologna on Monday night hoping to re-establish their lead of three and move even further ahead of either Inter or Juve.
Napoli were given a huge helping hand by captain Insigne, who was heavily criticised after Italy failed to reach a second World Cup in a row but opened the scoring and also laid on Politano's strike with a delicate free-kick.
"I'm disappointed that Italy aren't going to the World Cup, I can't do much apart from ask forgiveness from the fans," said Insigne, who was positive about his team's title hopes.
"We believe, we've always believed. There are still seven matches to go and they're seven big matches so we need to face them in the right way."
Defeat for Atalanta continued their dismal home record this season and leaves the one-time title hopefuls in seventh, eight points behind fourth-placed Juve and with little realistic chance of a place in the Champions League.