Lionel Messi and Inter Miami will feature in next year's expanded FIFA Club World Cup, FIFA president Gianni Infantino announced on Saturday.
Messi and his team-mates will kick-off the tournament in the opening game at Hard Rock Stadium, home of the NFL's Miami Dolphins, on Sunday, June 15, Infantino added.
The FIFA president was speaking on the field at Inter's Chase Stadium moments after Messi scored a hat-trick as the team broke the MLS regular season points record with a 6-2 win over the New England Revolution.
Miami, who this month won Major League Soccer's Supporters' Shield for the best regular season record, will take the qualification slot designated for the host nation.
"Inter Miami qualifies as the host country representative team on the basis of the club’s outstanding and consistent 34-match campaign that saw them secure the shield with two MLS matches to play," FIFA said in a statement.
The official champions of MLS are determined by the MLS Cup playoffs which begin next week and conclude with the final on December 7.
Miami are the favourites to win the playoffs but the FIFA decision to select the regular season winners ensures the involvement of the Argentine superstar.
The participation of the eight-time Ballon d'Or winner Messi is a much-needed boost to the profile of the new-look tournament, which FIFA hope will capture the imagination of the global television audience as well as fans in the United States ahead of the World Cup in 2026.
The competition could pit Messi against top European club opposition for the first time since he left Paris Saint Germain last year to move to Miami.
The 32-team tournament will feature title winning teams from each of FIFA's continental confederations.
Real Madrid, Manchester City and Bayern Munich are among the 12 European teams who have qualified for the tournament while Argentina's River Plate and Boca Juniors and Brazil's Flamengo are among six South American teams.
FIFA has yet to announce any broadcast deals or sponsorship contracts for the tournament and the competition has faced some opposition within the game.
Players union FIFpro and the European Leagues body filed a joint complaint to the European Commission against FIFA over the introduction of the tournament into the international match calendar.
Opponents of the new tournament have said it adds further congestion to an already crowded schedule and increases the workload of players.
The last version of the Club World Cup featured seven teams in a knockout format and was won by Manchester City who beat Brazil's Fluminense in the final in Saudi Arabia.
FIFA plan to hold the expanded tournament every four years although no host as yet to be chosen for the 2029 edition.
Meanwhile, Messi scored his second hat-trick of the week and Luis Suarez scored twice as Inter Miami beat the New England Revolution 6-2 to smash MLS's regular season points record.
Miami's win, in their final game of the regular season, took them to 74 points - one more than the previous record, set by New England in 2021.
Messi, who came off the bench in the 58th minute and led the late flurry of goals, has now scored 20 goals in 19 appearances in MLS with his former Barcelona team-mate Suarez also notching 20, from 27 games.
The challenge of breaking the record added some spice to the final game of the regular season with Inter having already secured the Supporters' Shield for the best record in the regular season to stamp themselves clear favourites in the MLS Cup playoffs which start next week.
Miami had trailed 2-0 before Suarez scored twice before half-time to send Gerardo Martino's team in level at the interval.
Goals from Argentine Luca Langoni and Colombian Dylan Borrero in the 34th minute had the home crowd chanting for Messi's introduction from the bench but it was Uruguayan Suarez who began the comeback.
A firm left-foot finish from the former Liverpool and Barcelona striker, pulled one back, after good work from David Martinez.
Then Suarez levelled with a fine solo finish, making space for himself and switching to his right foot before drilling home.
Messi, who had scored a hat-trick for Argentina against Bolivia on Tuesday, came off the bench in the 58th minute and immediately helped put the team ahead finding Jordi Alba who set up Benjamin Cremaschi for a tap-in.
New England thought they had drawn level with a goal from striker Bobby Wood but the effort was disallowed for handball following a VAR review.
Messi then made it 4-2, collecting a back-heeled pass from Suarez before brilliantly blasting into the far bottom corner.
The Argentine was on target again when he latched on to a superb pass from Jordi Alba and made no mistake and then he completed his hat-trick in the 89th minute when he met a volleyed cross from Suarez with a precise first time finish.
Messi's three goals came within an 11-minute spell and after his two month injury absence after the Copa America he now looks back to his best.
"I have the feeling that we have him in an ideal situation to face the most important part of the year," said Martino.
At the post-game celebration of the Supporters Shield success, club co-owners David Beckham and Jorge Mas were joined by Infantino who announced that the Shield had earned the team a place in the 2025 Club World Cup.
Elsewhere in the last round of the regular season in MLS, Montreal clinched a place in the playoffs with a 2-0 win over New York City.
The victory secured eighth place in the Eastern Conference and the Canadian side will play ninth-placed Atlanta United in the wildcard round on Tuesday for a chance to play Miami in the first round.
Atlanta took the final spot in the East with a 2-1 win at Orlando City.
There was a thrilling finale to the regular season in the Western Conference with the two Los Angeles clubs locked in battle for top spot and home field advantage throughout the playoffs.
LAFC left the field thinking their 3-1 win over San Jose was enough to have secured the top seed with LA Galaxy losing 1-0 to Houston.
But a stoppage time penalty, converted by Gabriel Pec, looked to have secured LA Galaxy the point they needed to secure first place and left LAFC fans, in California, watching on their phones desolate.
But then in the 11th minute of stoppage time, Houston grabbed a dramatic winner with a header from Daniel Steres against his former club, meaning that LAFC snatched top seed on goal difference - by a single goal.
LAFC will face the winner of the wildcard game between the Vancouver Whitecaps and the Portland Timbers while the Galaxy will host the Colorado Rapids in the first round.