Treviso are in eighth place, with twice as many wins as the Dragons, including in the reverse fixture - a 32-13 triumph at Stadio Comunale di Monigo at the start of December.
And Harries, who sat out the LV= Cup double header, is now calling on his side to retain the momentum they have built up since there last league encounter - a 30-11 defeat at Connacht.
"We had been building and going close in games but after the boys got the wins we really go into this month with high confidence," the 25-year-old told the South Wales Argus.
"They might be hit by international calls but they have a strong squad and play some good stuff. We just need to concentrate on our own form and put in another good performance.
"These past few weeks have been about building towards Treviso, so we must not put that to waste."
Captain Lewis Evans, and both Dan and Jonathan Evans have all returned to the Dragons team.
Lewis Evans is joined by prop Phil Price, while Nathan Buck is back from injury and Nic Cudd, who impressed against London Welsh, retains his place.
For Treviso, coach Franco Smith has No.8 Robert Barbieri and flanker Valerio Bernabo back in his starting XV.
Gideon Le Grange debuts in the competition at outside centre, while Pedro Di Santo returns to the squad and is a replacement after suffering an injury in the clash with Glasgow Warriors at the end of October.
And Smith is urging those selected to match the desire he anticipates will be on show from the Dragons.
"The Dragons are a very proud team, and they have their backs to the wall," he said. "It's an atmosphere where you have to work hard to earn the respect of the fans.
"They have had a difficult season, but the work has been put it. We know how much desire they will have to win this game.
"We need to be up to it physically. That will be the key, having the same passion for the game."
At Rodney Parade , 7.30pm.
Referee: David Wilkinson (IRFU, 18th competition game)
Assistant Referees: Jon Mason, Neil Perkins (both WRU)
Citing Commissioner: Gwyn Bowden (WRU)