The Italian coach has warned his men not to underestimate a supposedly weakened Atleti outfit ahead of their Champions League clash on Tuesday
Atleti are already guaranteed Champions League football after Christmas and are expected to rest a number of key players in St Petersburg.
However, Spalletti feels a weakened opponent might not necessarily play into Zenit's hands.
"I would prefer it if Atletico played their full-strength side because the absence of several players for the opposition would be a loss for us," Spalletti said at a press conference.
"I see a danger in the fact that my players might think that such an Atletico side is weaker but this is not the case."
Spalletti then went on to stress that the hosts will be without a number of first-team regulars as well, with Danny as perhaps the biggest name missing out.
He added: "However, we have some losses too as we will be without four or five regulars, such as Danny."
Zenit currently sit second in Group G with five points from four games, trailing leaders Atletico by seven points, but one point clear of third-placed Porto.