Juan has told skysports.com that he is confident Roma will overcome Arsenal in their UEFA Champions League tie.
The Gunners dominated the first leg at Emirates Stadium a fortnight ago and secured a 1-0 win thanks to a Robin van Persie penalty.
Juan was impressed by Arsene Wenger's side and expects another stern test at Stadio Olimpico, even though the injured Emmanuel Adebayor will be missing for the visitors.
The Brazilian defender believes Roma will turn in a much improved performance and will ultimately emerge triumphant.
"Roma arrive with many injuries for this match but it is important to offer the maximum effort to achieve success," he told skysports.com.
"The match is complicated and the rival is hard but this round is still open.
"Without Adebayor, Arsenal still have a strong attack with people like (Robin) Van Persie and Eduardo.
"Roma did not offer a positive image in London but this Wednesday I expect a different match."
Roma beat Real Madrid at the same stage of last season's competition and Juan insists there is no fear of Arsenal.
He said: "Beating Real Madrid gave us confidence and during this week we worked on the aerial game to avoid the biggest danger in Arsenal.
"My prediction is success for Roma. Extra-time? We are prepared for everything."