Italy's stuttering World Cup campaign showed no sign of improvement tonight as they struggled to an unconvincing Pool C win over brave Portugal at the Parc des Princes.
The Italians ran in just three tries against the amateurs, centre Andrea Masi scoring one in each half and flanker Mauro Bergamasco adding the other.
David Bortolussi kicked four penalties and two conversions but the Azzurri were sloppy and directionless, especially in the second half, and did not even claim a bonus point.
Portugal delighted a Parisian crowd of more than 45,000 with a try of their own in the first half, through lock David Penalva, and they battled gamely in only their third World Cup match.
On this showing, Scotland - who meet Italy in what is set to be a winner-takes-all match in St Etienne on Saturday week - have nothing to worry about.
The last game between the two sides saw Italy race to an 83-0 win in a World Cup qualifier last October, but this match was - somewhat unexpectedly - a genuine contest.
Masi's fourth-minute try came after Italy had started like a train.
The forwards laid the platform with phase after phase of possession, before the ball was fired out by fly-half Roland de Marigny to Masi, who scorched through a midfield gap to ground under the posts. Bortolussi converted.
A seventh minute yellow card to captain Marco Bortolami, for punching, momentarily took the wind out of the Italians' sails.
But they still held the whip hand and the lead was added to by Bortolussi penalties in the 17th minute and 29th minutes.
Italian errors soon surfaced, though, and after camping themselves in the Portugal half, the Azzurri were hit with a sucker-punch in the 33rd minute.
In Portugal's first meaningful attack, Duarte Pinto made deep inroads into the heart of the Italian defence, before the ball was recycled out to the right wing where Penalva was on hand to receive Diogo Gama's clever pass and dive over.
Pinto missed the conversion, and Bortolussi booted a late penalty to stretch Italy's lead to just 16-5 by the interval.
The Italians were simply dreadful in the second half.
The rising error count would have been alarming for coach Pierre Berbizier, and Portugal were by no means blown away.
Indeed, their line-out functioned well and some of their rare forays into Italian territory brought rounds of applause from the Parc des Princes public.
Italy were resorting to Bortolussi penalties to keep the Portuguese at arm's length, and he added his fourth in the 63rd minute.
They grabbed their second try, in the 73rd minute, when Bergamasco plundered over following a 10-yard rolling maul while Masi added his second after running onto de Marigny's chip over the defence.
But it did not stop Portugal celebrating at the final whistle.
Italy (16) 31 Portugal (5) 5
Italy: Tries: Masi 2, M. Bergamasco. Cons: Bortolussi 2.
Pens: Bortolussi 4.
Italy: Bortolussi, Canavosio, Canale, Masi, Pratichetti, de Marigny, Troncon, Lo Cicero, Ghiraldini, Castrogiovanni, del Fava, Bortolami, Parisse, M. Bergamasco, Vosawai.
Replacements: Griffen for Troncon (80), Aguero for Lo Cicero (64), Perugini for Castrogiovanni (64), Orlando for Vosawai (59).
Not Used: Ongaro, Bernabo, Galon.
Sin Bin: Bortolami (8).
Portugal: Tries: Penalva.
Portugal: Cabral, D. Mateus, Sousa, D. Mateus, Aguilar, D. Pinto, J. Pinto, Cordeiro, Correia, Spachuck, G. Uva, Penalva, Girao, J. Uva, V. Uva.
Replacements: Foro for D. Mateus (61), Gama for D. Mateus (31), Pissarra for J. Pinto (66), Mure for Cordeiro (61), Figueiredo for Correia (70), Da Silva for Spachuck (61), Murinello for J. Uva (64).
Ref: M Jonker (South Africa).Reuse content