LIONEL Messi is set to play his first game for Inter Miami on July 21 when the Major League Soccer side host Mexico's Cruz Azul in their Leagues Cup opener, managing owner Jorge Mas told the Miami Herald newspaper on Tuesday.

Messi and Miami have agreed terms on a deal and are finalising paperwork and visas after the Argentine great's announcement this month of his intention to join the club.

The 35-year-old will sign a two-and-a-half year deal worth $50 million to $60 million per year with an option to extend until 2026, according to the Miami Herald.

"Absolutely no changes in the roster rules. There are no categories or anything that is being changed to incorporate Lionel Messi onto Inter Miami’s roster," Mas added.

Having the seven-time Ballon d'Or winner on board promises to be a big boost for soccer in the United States, where its popularity trails the other four major North American men's professional leagues.

Mas defined Messi's arrival as "the seminal moment" in the history of U.S. soccer as MLS aspires to be one of the best leagues in the world.

"I think there will always be a before and after Messi when we talk about the sport in the United States," Mas said.

"I have very strong-held belief that we can create in North America and the United States if not the greatest league, one of the top two leagues in the world.

"Lionel Messi is coming to this country to win cups and make a difference. I think it's incumbent upon myself and my partners in the league, the other owners, to seize the moment."

News of Messi joining Miami had its first effects in a matter of hours, sending ticket prices soaring 1,034% and increasing the number of followers on the team's Instagram account from one to eight million.

Miami are currently bottom of the Eastern Conference standings - seven points from ninth place, the final spot which would give them a chance of qualifying for the playoffs.

The Leagues Cup is an annual competition between MLS and Mexico's Liga MX clubs.