The Italian forwards dominated possession and their loose forwards reveled in the chances their tight five gave them with flanker Andrea de Rossi having the day of his life.
The first half ended with Italy ahead 20-17 and they had more possession, beginning when prop Giampiero de Carli barged over from close range. Wales replied with a try by lock Steve Williams and scored again when Gareth Thomas fed Tom Shanklin, who put Wales 14-7 in front after 14 minutes.
Italy came back with debutant hooker Festuccia barging over and a penalty exchange took it to 17-all until Dominguez dropped a goal just before the interval.
The key try came when a misunderstanding between Dwayne Peel and Colin Charvis saw Troncon snap up the ball and New Zealander Matt Phillips scored and then Dominguez popped over another drop shot. The last score came in injury-time as Iestyn Harris side-stepped sweetly and Peel scored far out.
Italy: P Vaccari; Mauro Bergamasco, C Stoica, G Raineri (Mirco Bergamasco), D Dallan; D Dominguez, A Troncon (capt); G de Carli, C Festuccia, R Martinez-Frugoni (temp S Perugini), M Bartolami, C Bezzi, A de Rossi, M Phillips, A Persico.
Tries: Giampiero de Carli, Carlo Festuccia, Matt Phillips. Cons: Diego Dominguez (3). Pen: Dominguez, DG: Dominguez (2).
Wales: R Williams; M Jones (C Sweeney), T Shanklin, L Davies (M J Watkins), G Thomas; I Harris, D Peel; I Thomas, M Davies (G Williams), B Evans, R Sidoli, S Williams (Dafydd Jones), M Owen, C Charvis (capt) (Gavin Thomas), M Williams.
Tries: Steve Williams, Tom Shanklin, Dwayne Peel. Cons: Iestyn Harris (2). Pen: Harris.
Referee: Joel Jutge (France).
