The San Paolo outfit, who blazed a trail at the start of the season, are now nine points shy of league leaders Juventus having suffered a shock 2-0 defeat at Chievo that extended their winless run to a fifth game.
Talismanic striker Edinson Cavani has failed to score in eight appearances, with Napoli finding the back of the net just twice since their last victory - a 2-0 home win over Catania on February 2.
Atalanta might well arrive on the back of two straight wins but the northerners are not renowned for keeping clean sheets, with Hamsik desperate to take advantage on Sunday.
He told Gazzetta.it: "We have certainly been expecting a lot more of ourselves. Performances have not been what we imagined they would be and if you don't score, you can't win.
"But I'm convinced we'll snap this bad sequence of results and that we'll take all three points against Atalanta."
Defender Miguel Britos is Napoli's only injury concern but head coach Walter Mazzarri must decide whether to keep faith with Cavani or instead partner Goran Pandev with young striker Lorenzo Insigne.
Franco Brienza, Gian Bellini, Daniele Capelli, Lionel Scaloni and Guido Marilungo are sidelined through injury for Atalanta while striker Giuseppe De Luca joins his manager Stefano Colantuono in the stands to serve a one-match ban.
The fiery Nerazzurri boss left his technical area to question the referee during last weekend's 2-1 win over Pescara and will be barred from the San Paolo touchline as a result.
Atalanta defender Guglielmo Stendardo spoke on Colantuono's behalf, therefore, in urging his team-mates to reach 40 points as soon as possible.
"The two victories over Siena and Pescara have calmed us down a little but we still need seven more points to be sure of our survival," he said.
"Getting a result in Naples would be a massive deal for us but we know that we can expect a very difficult match."