Defending champions Spain also got their campaign off to a successful start, and there were opening wins for Puerto Rico, Georgia, Greece, Brazil and Serbia on the competition's second day.
The United States finished seventh at the last World Cup in China four years ago and headed into this year's edition in the Philippines, Japan and Indonesia with a talented young squad with no previous tournament experience.
They clawed their way back from a 10-point deficit in the first quarter to take control against New Zealand in Manila, going on to win 99-72.
Head coach Steve Kerr said New Zealand's ferocious start made it "a really good game for us to experience".
"One of the things that we've talked to our team about is how excited everybody else is going to be to play against us," he said.
"New Zealand came out and hit us in the mouth and they were great -- that's good, it's good for us to feel."
Paolo Banchero, last season's NBA Rookie of the Year with the Orlando Magic, led the United States in scoring with 21 points, followed by Jaren Jackson Jr. and Austin Reaves on 12 apiece.
"Obviously not the start we wanted," said Los Angeles Lakers shooting guard Reaves.
"We'll go back and watch film and learn from that but our intensity and our physicality after that first five minutes was much better."
New Zealand made their intentions clear with a pre-game haka and they carried that aggression into the first quarter.
The Tall Blacks had four players scoring in double digits, led by Reuben Te Rangi with 15 points.
"It was amazing seeing Kiwis out in those stands," said Te Rangi.
"They've travelled a long way to come here and support us, and it's awesome to be able to play in front of them and put on a spectacle for them."
In the day's other Group C game, Greece beat Jordan 92-71.
Doncic dazzles
In Group F in Okinawa in southern Japan, Doncic scored 37 points and had seven rebounds and six assists as Slovenia beat Venezuela 100-85.
The four-time NBA All Star is appearing at the World Cup for the first time, after helping Slovenia to a fourth-place finish at the Tokyo Olympics two years ago.
He missed out on a place in the NBA playoffs with the Dallas Mavericks last season but he said it made "no difference" to what he wants to achieve with Slovenia.
"It's special playing for your country, representing your country -- you are always motivated, no matter what happens in the season," said the 24-year-old.
"Obviously it was disappointing we couldn't make the playoffs but playing for your country is special.
"It's from the heart. Representing your country is amazing."
Georgia beat Cape Verde 85-60 in the other Group F game, in a matchup of tournament debutants.
Spain lifted the Naismith Trophy four years ago and they got their title defence off to a winning start, beating Cote d'Ivoire 94-64 in Jakarta.
Willy Hernangomez led Spain in scoring with 22 points, followed by Usman Garuba on 12 and Juancho Hernangomez on 11.
Also in Group G, Brazil beat Iran 100-59 but lost Raul Neto to a ruptured tendon in his right knee.
South Sudan looked headed for a win in their tournament debut when they took a 12-point lead against Puerto Rico in Group B.
But the Puerto Ricans fought back to take the game to overtime and went on to claim a 101-96 victory.
South Sudan head coach Royal Ivey said the game was "a learning experience" but rued the missed opportunity.
"There are no moral victories for us," he said.
"We had that game and we gave it away."
Serbia beat China 105-63 in the day's other Group B game.
