Roberts, who was a fitness doubt before the match, had admitted to being more than a little nervous about his place in the side in the build-up to the Azzurri clash after his half-time replacement Scott Williams scored a last-gasp try to down England.

However the Blues centre made sure he answered any doubts in fine style as Wales, helped by 11 points from the boot of Leigh Halfpenny and Alex Cuthbert's second international try, saw off Italy.

It was largely a frustrating afternoon for a capacity Millennium Stadium crowd with a Rhys Priestland penalty, and three points from Mirco Bergamasco's boot, the other scores.

Wales dominated the early exchanges but some impressive Italian defence - and some indiscipline from the home side -meant the scores were level until the ninth minute.

Sergio Parisse was penalised for offside and Halfpenny's lofted penalty from a distance was a successful one and Wales were three points to the good.

But the Azzurri were level when Mirco Bergamasco slotted a penalty of his own two minutes later after skipper for the day Gethin Jenkins was penalised at scrum time.

Having shown their attacking intention by kicking a penalty to the line out minutes earlier Wales, and Halfpenny, couldn't resist a penalty from in front of the posts to make it 6-3 after Andrea Masi was penalised for not rolling away.

The home side were frustrated again just before the half hour mark. Halfpenny thought he was in for a score with a one-on-one with Parisse but the Italian skipper hauled him down and forced a knock on.

It was one way traffic but with their line-out - the only real point of concern in their opening three wins - again creaking the home side were unable to break the Azzurri defence.

Full-back Halfpenny - again replacing Priestland on kicking duties - slotted his third penalty from as many attempts after Italian flanker Simone Favaro was penalised.

The Azzurri then showed their attacking intent by opting to shun a kick at goal for a lineout in the corner but Wales secured a penalty and it was 9-3 at the break.

With Italy again frurstating the home side for the opening ten minutes of the half Wales notched their first try of the game from a turnover ball.

Parisse was the guilty party for the Azzurri and after working the ball wide Roberts exploited the overlap, eventually crossing under the posts having picked up the ball inside his own half.

Halfpenny took his tally to 11 points with an easy conversion as Wales looked to turn the screw. A multi-phase move looked sure to breach the Azzurri defence again minutes later but it was the home side who were eventually penalised just yards from the Italy line.

The home crowd sensed blood but there hopes were dealt a blow when Halfpenny blotted his copybook by being yellow-carded after tackling Parisse in the air.

Despite being a man down it was Wales who registered the only points during that ten-minute period however with Priestland kicking a penalty to make it 19-3.

The gloss was put on Wales' win in the later stages with Cuthbert's score, like Roberts exploiting a mis-match on his way to running in from distance.

Priestland missed the conversion attempt from out wide but Wales' pursuit of a third Grand Slam in eight seasons ultimately remained alive.