The Giallorossi won their first 10 games of the league season, but have drawn each of their last three matches, and the Brazilian admitted that he and his teammates have been suffering from tiredness.
"After 10 consecutive victories, it was only normal that a little fatigue would creep in, above all because most of us are internationals and make long journeys," he told Roma Channel.
"Having said that, we cannot keep dropping points the way we have done recently, especially on home turf.
"The time has come to show our strength, starting from Bergamo."
Roma are second in the Serie A table ahead of this weekend's game.