United States head coach Mauricio Pochettino lavished praise on his players and the American fans after his side romped past Paraguay 4-1 at the Los Angeles Stadium.
"I'm so so proud," said Pochettino. "I think players and the staff deserve credit for this performance and the feeling."
Damian Bobadilla gave the co-hosts the perfect start when he scored an own-goal after seven minutes.
Folarin Balogun took centre stage for the rest of the half to the delight of the vast majority of the 70,000 spectators in the arena.
The 24-year-old, who plays at the French Ligue 1 outfit Monaco, doubled his side's advantage after half an hour and he made it 3-0 on the stroke of half-time.
Mauricio pulled one back for Paraguay after 73 minutes but there was no comeback.
Gio Reyna added the gloss for the co-hosts in stoppage-time.
Pochettino praises team performance
"Of course I need to praise the principal actors," added Pochettino who took over from Gregg Berhalter in September 2024.
"And also the fans. Amazing. They were amazing and on behalf of the whole team, I say a massive thank you to the fans because the energy that they translated to the team was amazing.
"We can do amazing things if the fans are in this and are in this way."
The US play their second game in Group D against Australia on 19 July in Seattle before finishing the pool stqges against Turkey in Los Angeles.
"This is only the start," warned Pochettino. "There are still two games to play. We need to enjoy this kind of start to the tournament but remember that we need to keep going and keep trying to improve and do better because all the games are going to be very competitive."
Before the match, the opening ceremony included sets from Katy Perry who was accompanied by singers Future, Tyla, Anitta and K-pop star Lisa.
Performers danced around a giant World Cup trophy beneath enormous "FIFA" letters in the gold. President Donald Trump was a notable absentee from the array of VIPs.
He wished the team good luck in a pre-match telphone call.
Of the three co-hosts for the first 48-team World Cup, only Canada have failed to win.
They drew 1-1 with Bosnia and Herzegovina on Friday night in Toronto.
On Thursday at the Estadio Azteca, Mexico beat South Africa 2-0 to launch the 23rd edition of the tournament.
