The USA kick-started its campaign with a 4-1 hammering of Paraguay in Los Angeles.

Folarin Balogun scored twice on the back of an early own goal from Damian Bobadilla, with Giovanni Reyna capping off the Group D rout in second-half stoppage-time.

The USA's opening goal in the seventh minute was the third-fastest goal scored by a host nation in its opening match at the FIFA World Cup, and set the tone for a dominant display.

Pochettino was full of pride, but the Argentinean was quick to stress his team must only see this as a starting point, with fixtures against Australia and Turkiye to come.

"So, so proud. Players and staff deserved big credit for this performance," he said.

"The most important thing is the performance and the feeling. We know it is only the start and it is nothing. It is only one game. Now we need to be intelligent to keep [going] in that direction.

"But we are so happy because the first game is always so difficult, hosting the World Cup, the expectation, but we managed the expectation and pressure. The first 45 minutes were amazing, difficult to find a team to play like this. So happy and so proud."

Star player Christian Pulisic had to be taken off at half-time with a calf issue, a sour note on an otherwise excellent day for the home side.

"He received a kick in his calf and he felt tight at the end of the first half," Pochettino said of Pulisic's injury.

"We didn't want to take any risks. It was difficult for him to walk, but we hope that it is not a big issue and he can be ready for the next one."

Pulisic himself also looked to calm fears.

"I just got a bit of a kick in the first half, so I'm really hoping that it's nothing," he said. "Taking a little bit of precaution today, but I'm hoping I'll be fine the next few days.

"I've had similar things before, staying positive. I don't think it's anything."

Paraguay has now failed to win in its past four World Cup games, and coach Gustavo Alfaro conceded his team had been on the end of a harsh lesson.

"At a [FIFA] World Cup you have to leave emotions to one side," Alfaro said.

"What matters are decision-making, concentration and the details.

"United States won with absolute justice and clarity. They surpassed us tactically, they surpassed us technically and they surpassed us physically."