Webster said: "We were clearly blown apart by a New Zealand team that capitalised on our every mistake on Tuesday. We weren't able to get into our game plan due to total lack of possession and territory. However, we have to try and forget about the New Zealand loss for now, because with a four day turnaround between each match, there is no time to dwell on it.
"We showed we are not a bad team with our opening win over Argentina, and we are determined to show that again tomorrow, and in our two play-off games next week.
"Wales finished seventh in this competition last season, and sixth the year before, with three good performances and results, we can better that finish, which is what we are focussed on doing now.
"We beat Italy comfortably in the Six Nations with 14 men, but as hosts who have not yet won a game in this tournament, they will be determined to put in a good performance against us in front of a big home crowd.
"It is down to us to stick to our game plan and come away with the spoils."
There are 10 changes and one positional from the side that started on Tuesday. Ross Jones (full back), Rheon James (centre) and Lewis Smout (loose head) make their first starts of the tournament, Matthew Morgan and Jonathan Evans return at half back and Macauley Cook returns as captain, with fellow lock Lloyd Peers ruled out with an elbow injury.
Also returning to the starting line-up are wing Eli Walker, prop Will Taylor and back rows Luke Hamilton and Ben Thomas. Liam Williams switches back to right wing from full back.
Webster added, "This is a long tournament and we have to manage the squad accordingly. I have every confidence in every one of the 26-man squad to go out and prove what they are capable of."
Wales v Italy (Saturday 18 June, KO 5.10pm, Stadio Monigo, Treviso):
Ross Jones (Ospreys / Bridgend); Liam Williams (Llanelli), Owen Williams (Blues / Cardiff), Rheon James (Scarlets / Carmarthen Quins), Eli Walker (Ospreys / Swansea); Matthew Morgan (Ospreys / Swansea), Jonathan Evans (Dragons / Newport); Lewis Smout (Blues / Pontypridd), Kirby Myhill (Scarlets / Llanelli), Will Taylor (Ospreys / Swansea), Macauley Cook (capt, Blues / Cardiff), Cory Hill (Blues / Pontypridd), Luke Hamilton (Blues / Glamorgan Wanderers), Thomas Young (Blues / Cardiff), Ben Thomas (Ospreys / Bridgend).
Replacements: Jamie Sollis (Dragons / Cross Keys), Rhodri Jones (Scarlets / Llanelli), Owen Sheppeard (Blues / Pontypridd), Edward Siggery (London Irish), Lewis Jones (Blues / Pontypridd), Steve Shingler (London Irish), Iolo Evans (Scarlets / Llanelli)