Lionel Messi's Argentina and Kylian Mbappe's France, the two teams who contested a thrilling World Cup final four years ago, roar into the 2026 tournament on Tuesday.
Argentina, who won that thrilling contest in Doha in a penalty shootout after it finished 3-3 following extra time, take on Algeria in Kansas City.
Messi is set to play in a sixth World Cup and Argentina coach Lionel Scaloni said the 38-year-old linchpin of his team "looks good" despite suffering a hamstring injury playing for club side Inter Miami in late May.
"Everyone wants to see him out on the pitch, not just Argentinians, because of the impact he has on people," Scaloni said at his pre-match press conference.
"He has always been crucial for us and now he will be even more so. He looks good."
Messi proved his fitness by coming on as a substitute and scoring in a warmup against Iceland last week.
"He's a competitive animal," said centre-back Nicolas Otamendi. "He makes you keep trying, he doesn't let you relax."
France and their potent attack featuring Mbappe, Ballon d'Or winner Ousmane Dembele and flying winger Michael Olise open their account against Senegal in New Jersey.
The French will be desperate to avoid any repetition of the opening-day defeat by the Senegalese that they suffered at the 2002 World Cup in South Korea, a result which led to the then-reigning champions crashing out in the group phase.
"The first match is very important but it's not decisive. Starting with a win in a four-team group is ideal and always the objective," France coach Didier Deschamps said on Monday.
"But the one thing we can't measure or quantify is the emotional aspect. Some players might tense up with the atmosphere around the match," Deschamps warned.
France have reached the final in four of the last seven World Cups, winning two and also losing two more on penalties.
HUNGRY HAALAND
Erling Haaland makes his World Cup finals debut for Norway against Iraq after his country qualified for the first time since 1998.
Haaland has just finished as the Premier League's top scorer for the third time in four seasons at Manchester City and boasts a remarkable record of 55 goals in 50 caps for his country.
"Hopefully he'll have a very big impact," said Norway coach Stale Solbakken, who was in the squad as a midfielder the last time Norway played at the finals in France.
Iraq's Australian coach Graham Arnold believes his team can pull off an upset.
"We've got to perform to our best and try to shock the world," Arnold said.
"Qualification is not enough. I want more," he added. "We've only got everything to win and not to lose.
In Monday's action, one of the pre-tournament favourites, Spain, were held to a shock goalless draw by tiny Cape Verde, one of the debutants.
Even the introduction of Barcelona star Lamine Yamal as a second-half substitute made no impact.
Iran played out a 2-2 draw with New Zealand in Los Angeles as the Islamic Republic's fraught World Cup began with tens of thousands of California's Iranian diaspora in the stands.
Afterwards, coach Amir Ghalenoei said Iran was the "most oppressed team in the World Cup" after his players were suddenly informed they must travel back to Mexico immediately after the game.
It was the latest logistical nightmare for an Iran squad that arrived at the tournament being co-hosted by the United States, Mexico and Canada under the shadow of a bitter diplomatic row between Tehran and Washington.
The changed their training base from Tucson, Arizona to Tijuana in Mexico shortly before the tournament.
In Seattle, an upset looked on the cards as Egypt took the lead through Emam Ashour in the first half against Belgium.
But veteran Belgium striker Romelu Lukaku came off the bench in the second half and his physical presence caused Egypt defender Mohamed Hany to concede an own goal and give Belgium a point.
Uruguay had to come from behind to grab a point against Saudi Arabia in Group H.
--------------------------------
Where to watch the FIFA World Cup 2026™
Fans can watch every FIFA World Cup 2026™ match live on DStv Premium, Compact Plus, Compact, Family and Access. All matches are also available to stream on supported packages, ensuring flexible viewing options wherever you are.
How to stream the FIFA World Cup 2026™
With DStv Stream, you can follow every match anytime, anywhere. Download the app and enjoy seamless live streaming on the go.