Wales did enjoy all the early possession and territory, but struggled for collision dominance as they went through the phases.
Italian indiscipline gifted them an attacking line-out and the Welsh maul, which had stuttered against Ireland, went back to being a weapon with the pack driving Williams over for her third try of the campaign.
Italy responded in style with fly-half Veronica Madia showing her creativity with the boot, her cross-field kick just beating Alyssa D’Inca on her wing.
But the hosts were not to be denied when some loose kicking from Lleucu George saw Sara Seye and Elisa Giordano burst through some weak tackling, with returning scrum-half Stefan finishing under the posts.
Sillari added the conversion and, sensing it might be a close game, a later penalty to give Italy the lead.
Momentum then shifted back to Wales and a fumble under the high ball from Minuzzi gave them a good attacking platform, but basic errors crept in and the visitors could not capitalise.
But they were given another chance on the stroke of half-time. The attack once again came off line-out ball and the forwards showed good patience, keeping it tight until Pyrs pounced from close range.
Bevan added the conversion to give Wales a 12-10 half-time lead, the first time this campaign they went down the tunnel ahead.
But the optimism was short-lived as Italy came out with a change of tactic as they chose to engage in a kicking battle with George.
It almost paid off with a chip setting up Giordana Duca, who would have been through if not for a last-gasp tap tackle from Jasmine Joyce-Butchers.
Italy kept coming with wave after wave of attack as Wales struggled to live with their offloading game and when points were on offer Silari took the opportunity to kick Italy back in front.
Lynn responded by making some early changings, with Alex Callender, Hannah Bluck and Carys Phillips all coming on to the field.
But they were not able to make an impact as Italy kept piling on the pressure and managed to get the ball out wide to Granzotto, who did well to ride the defensive tackle and get the ball down in the corner.
Wales desperately needed to get a foothold, but they could not live with the scintillating Azzurre attack.
Italy went for the jugular and opted for a tap penalty in front of posts, and while the defence did well to repel the charging Sara Tounesi, they could not prevent Turani from stretching over the line.
The fourth try came from the full-back Minuzzi, whose outstanding 50-22 launched Italy upfield. The forwards then carried hard before Minuzzi ran a fine line to cut through the defence.
Wales were reduced to 14 players when Natalia John was sent to the sin bin for a high tackle, and took full advantage as Granzotto completed another fine finish in the corner while Muzzo crossed at the death to pile on the misery.
