Eusebio Di Francesco’s men came from 4-1 behind to end Barca’s Champions League hopes in the last round.
They now face a similar task in overturning a 5-2 deficit against Liverpool in the second leg of their semi-final clash.
Nainggolan says Roma will draw inspiration from their comeback against the La Liga champions but admits repeating the feat against Liverpool will be much more challenging.
“It was difficult against Barca and we need it so we need to believe in what we do,” said the Belgium international.
“It will be more difficult than against Barca because physically they are a better team and the only thing we need to try is to try and score three goals and not concede.
ROMA stars were pictured training today in shirts dedicated to Liverpool fan Sean Cox - who was left badly injured in crowd trouble prior to last week's Champions League semi-final at Anfield.
Edin Dzeko Twitted
“I am afraid Liverpool players were more consistent. In some parts we did well at the beginning and end but not the whole 90. At Barcelona, we did it for large spells of the game.
"We cannot afford to repeat the mistake by conceding the goals. We know what we have to do.”
Roma boss Di Francesco mirrored the views of his midfield ace ahead of the showdown in the the Stadio Olimpico.
“It will be more difficult than against Barca because physically they are a better team”
Radja Nainggolan
He said: “In terms of the Barcelona match, I would do a copy and paste like you would on Microsoft Word but in the minds of the player and physically, in order to compete against Liverpool, we need to raise the bar against Liverpool with physical effort.
“Then comes attitude, approach to the game and the fact we need to try and score an early goal and to have the fans behind us even more.
“From a motivational point of view, we have the desire to complete this comeback and put everything on the pitch and try and do something great and massive.”
