Italy 30 Wales 22
Italy claimed only their second win since joining the Six Nations after defeating Wales 30-22 in the opening match of the 2003 tournament at the Stadio Flaminio.
Both teams scored three tries, but Diego Dominguez proved the key, the Stade Francais veteran fly-half kicking 15 points with his reliable boot to take his tally to 980 since making his debut for the Azzurri in 1991.
The last time Italy tasted victory in the Northern Hemisphere's elite tournament was against Scotland in 2000, their debut year.
Dominguez's kicking aside, Italy's triumph owed much to their back row who were outstanding.
Italy started positively in the early spring sunshine and took a deserved lead in the fourth minute to get the home crowd on their feet.
Captain Alessandro Troncon collected from the scrum a few yards out and fed Carlo Festuccia with a delightful back-handed reverse pass.
The Italy hooker ran into stiff Welsh resistance, but was well supported by prop Giampiero De Carli who ran in the try which Diego Dominguez converted.
Italy's joy was short-lived as Wales scored two tries in seven minutes.
Northampton lock Steve Williams took advantage of some weak Italian tackling to go in behind the posts before Saracens' centre Tom Shanklin went over with a superb individual effort which began deep in his own half.
Both tries were converted by Cardiff stand-off Iestyn Harris.
Italy levelled the scores with a controversial score in the 21st minute.
The Welsh players complained that Troncon was deliberately blocking to allow Festuccia to run in the try, but French referee Joel Jutge allowed it to stand and Dominguez converted.
Wales, who beat Italy in Cardiff 44-20 last year, regained the lead in the 28th minute thanks to a Harris penalty, awarded for an offence in the ruck, before Dominguez restored parity after the visitors had strayed offside.
With the first-half drawing to a close and Italy's back row dominant, Dominguez found the time and space to place a drop goal between the posts from 15 yards to give the hosts a 20-17 interval lead.
Dominguez was then short with a drop-goal attempt as Italy continued to press forward after the break, and their attacking strategy paid off in the 61st minute when they scored their third try.
Troncon gained possession from a Welsh scrum and fed Andrea De Rossi whose quick hands set up Italy number eight Matthew Phillips for an easy score which Dominguez converted.
Dominguez's cheeky drop goal increased Italy's lead in the 73rd minute before
Dwayne Peel went over for Wales' third try to ensure a nail-biting finale. But Italy held on for a memorable victory, prompting a good-natured pitch invasion by their delirious fans.