The Germany international striker is missing for the capital-city side's trip to San Paolo on Saturday but despite this, his boss remains confident of getting a result
The capital-city side have had an impressive start to the campaign so far, and sit in second place in the standings ahead of this weekend's fixtures.
However, Reja's men will have to do without the Germany international for the clash in San Paolo, as he picked up a muscular injury in his nation's 3-0 win over Netherlands in midweek.
Despite holding the veteran attacker in high regard, the 66-year-old feels his team can get a result without Klose.
"Klose is irreplaceable but I have a reliable group, and tomorrow we'll play the game confidently," Reja told reporters in a pre-match press conference.
"We have had excellent performances so far this season and we would like to continue this.
"Napoli have an advantage because they have not played for three weeks, recovering energy. [Edinson] Cavani, [Ezequiel] Lavezzi and [Christian] Maggio are in form.
"But it is a game within our reach; we respect our opponents but don't fear them," he concluded.