Naft were beaten 2-1 by Uzbek champions Pakhtakor in their opening Group B match.
Mansourian believes his side will get the job done if they stay focussed for the whole game.
"Although we played good football in the previous match against Pakhtakor we had some mistakes which resulted in a defeat.
"That game was a big test for us and I have told my players that a football match is 95 minutes so they have to give their best until the final whistle," said Mansourian.
"We know what we want from the match and my players are all ready to take the three points. We know Al Ain is one of the best teams in Asia.
"The club's officials have counted on us in the AFC Champions League so we will send Al Ain home empty handed," he added.
Al Ain coach Zlatko Dalic has been impressed by the domestic form of Naft but has been bolstered by the availability of star playmaker Omar Abdulrahman who has recovered from injury.
Ain drew their opening game 0-0 against Al Shabab of Saudi Arabia in Riyadh.
"Any team that has leapfrogged Esteghlal, Sepahan and Foolad in the Iran Pro League table is definitely a strong team, and in the AFC Champions League there aren't any weak teams in the competition," said Dalic.
"We are expecting a difficult game but we are here to play good football and get a good result, even a draw would be good for us," he added.