Howley had watched his team struggle in the first half at the Stadio Olimpico, but Davies’s introduction at the break for the injured Dan Biggar saw the game turn on its head.
The young Ospreys fly-half, who only made his senior international debut in November, showed some lovely touches in his 40 minutes on the field, helping Wales score 30 unanswered points in the Italian capital for a first opening-round Six Nations win since 2012.
Jonathan Davies, Liam Williams and George North all crossed for tries in the final quarter – Sam Davies creating the last of those scores – with Leigh Halfpenny adding 18 points from the tee. It leaves Wales top of the table ahead of welcoming Eddie Jones’s unbeaten side to Cardiff on Saturday.
Biggar and North, who suffered rib and thigh blows respectively, will be assessed to see if they can feature in the Principality Stadium clash, but Howley believes Sam Davies is more than capable of stepping into the famous red No10 jersey if needed.
“Dan took a bump to the ribs. We will wait to the morning to see how he is,” said Howley.
Rob Howley praised Sam Davie's impact from the bench
Sam Davies was brought on for the injured Dan Biggar at the break
“Sam played well. He came off the bench in a difficult situation and he controlled things nicely. He showed a lot of composure and created space for other players around him.
“It was a shame to lose Dan, but I said in the autumn that Sam is ready to start a game. He’s got a lovely left boot and showed some lovely touches.
“The competition for places is something we have talked about and it’s nice to have a headache as the coach. We’ll have to wait and see how Dan is, but Sam has come in and put pressure on.”
Sam Davies came on with Italy leading 7-3 thanks to Edoardo Gori’s try and a conversion from Carlo Canna. It was an advantage their committed first-half display deserved, Wales’ only response coming from a Halfpenny penalty.
Conor O’Shea had emphasised the importance of his side playing for the full 80 minutes in the build-up to this game, but they failed to back up his words with a performance as they fell away after the break.
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The home side coughed up 16 penalties and saw prop Andrea Lovotti sent to the sin bin for failing to drive straight at the scrum. That allowed Wales to strike and Jonathan Davies and Williams crossed for tries within six minutes.
North’s late salvo, after being teed up by a jinking Sam Davies, set up a search for a bonus point, but Wales ultimately fell just short of a fourth try.
England are next up and with a short turnaround, Howley knows his team must improve further. Wales flew out of Italy on last night and straight into cryotherapy treatment to maximise their recovery just six days out from their second Six Nations fixture.
“We want to be relentless with and without the ball and at times we didn’t do that as I would have liked,” Howley added. “We will need to put England under more pressure than we did to Italy today.
“All of our focus has been on the first two games and that started with Italy. But we have done a lot of analysis on England.
“It’s important we started well and I’m glad we can go into the next game with some self-belief and a bit of confidence.”
While Wales look forward to England, O’Shea was left frustrated by referee JP Doyle’s interpretation of the breakdown.
“Our scrum, maul and defence was outstanding in the first half and that’s a real positive,” said the former Harlequins boss.
“I’ve got no doubt the penalties given against us were correct, but what I don’t agree with is that only five were given against Wales.
“There’s no point going into specifics. Watch the first two minutes of the match and the scene is set.”
Italy – Try: Gori. Con: Canna.
Wales – Tries: J Davies, L Williams, North. Cons: Halfpenny (3). Pens: Halfpenny (4).