They travelled to champions Glasgow Warriors last weekend but, despite putting in an improved showing, failed to come away with even a losing bonus point with Simone Favaro dotting down for the hosts in the final play of the game.
Harris is well placed to comment on the team's performances having appeared in all four matches this campaign and he believes the players are getting stronger with each game.
"As a pack we had the mindset to work hard for each other and that's not going to stop," Harris told the South Wales Argus.
"We need to improve every week, sometimes it's how you lose and the guys showed a big improvement in attitude against Glasgow.
"It was a step forward and we have to keep moving in the right direction because it's going to be another tough game.
"Italian sides are always very physical and play a forward-orientated game so we have to perform well as a pack because that's where the game will be won and lost, as always.
"There were positives to take from Glasgow but we were still our own worst enemy with mistakes and indiscipline. If we can sort that out and keep improving then I am sure we'll go on a good run."
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