The Neopolitan side are on a 12-match unbeaten run in Serie A this season with 32 points from 12 games and, despite the Anfield defeat, they qualified for the Champions League knockout stages as Group A winners.
AtalantaAtalanta are also in great shape, having lost just once in Serie A, and have 27 points from their 12 matches, a club record in the top flight.
Gian Piero Gasperini (63) took over in 2016 and led Atalanta to their first Champions League qualification in 2019 followed by two more seasons in Europe's elite club competition although they failed to qualify for Europe last season.
"We will need quality and physical strength. They (Atalanta) have been shaped in the correct way and then there is Gasp who is a veteran and a terrific one," Spalletti told reporters.
"At Bergamo there will be a test which is very similar to (Anfield), it would be a confirmation of the steps we took forward... but I am calm because the team trained really well yesterday."
Napoli said that Khvicha Kvaratskhelia (21) would not play on Saturday due to acute lower back pain after training.
The Georgian - nicknamed 'Kvaradona' after former club hero Diego Maradona - has played a key role since joining the club in the close season, scoring six goals and registering five assists in the league.
Spalletti added that Napoli would face a lot of risks against Atalanta as their players work well collectively and his side need to be aware of their own strengths to win.
"We'll need to do everything, interpret the changes in the game itself, and we've seen that the (Atalanta) team can play in the open and know how to behave in different situations," he added.
"We need to be at that level if we want to have important ambitions."
