Rui Vitoria says his Benfica side will only know the effect of Zenit's lack of match action come kick-off in Tuesday's Champions League last-16 first-leg showdown.
While Benfica go into the clash at the Estadio da Luz off the back of a defeat to Primeira Liga rivals Porto, Andre Villas-Boas' Zenit have not played a competitive match since their final Champions League group meeting with Gent in December.
Their Russian Premier League title defence does not begin until March and former Porto coach Villas-Boas acknowledged Zenit face a challenge to regain match sharpness.
Opposite number Vitoria is unsure what impact it will have, telling reporters: "They are a strong team, with quality players and a quality coach.
"They are a team with a great connection with each other, who have played together for a long time. Also they know Portuguese football and have maturity at this level.
"Even with such a break, tomorrow will be about mental aspects, not just the physical ones. We do not know if [their lack of games] will be an advantage for us or not.
"Only when the referee starts the game will we see that. But this does not invalidate what we intend to do or what we look at. We really want to win the game.
"We are not here to talk about tactical issues, because that would give an advantage to Andre. In the same way they will have to be careful with us, we will have to be careful with them, as is normal in any game."
Benfica made it through a tricky Group C behind Atletico Madrid as Vitoria's men reached the knockout rounds for the first time since their run to the quarter-finals in 2012.
Prior to this season, Benfica reached the knockout stages in just one of their previous seven Champions League campaigns, with Vitoria adding: "We are very happy to be in the top 16 teams in Europe.
"Tomorrow there will be four teams playing and Benfica is one of them. We are happy, but we are not euphoric, because this is the place for Benfica.
"We will not think about managing the next game, our thoughts are one by one... and tomorrow is to win."