Alvarez, who won a silver medal in the 5,000 metres team relay at the 2014 Winter Olympics in Sochi, has since turned his attentions to baseball and made a Major League Baseball (MLB) debut for the Miami Marlins last season, when the team was hit by a COVID-19 outbreak.

The 31-year-old infielder is not currently on the Marlins' 40-man roster, so was able to be called up by the US national team and duly was.

The training squad, which will need to be reduced to 26 players come the qualifier, is a mixture of youth and experience.

Outfielder Matt Kemp, catcher Matt Wieters, third baseman Todd Frazier and pitchers Edwin Jackson and David Robertson are all former MLB All-Stars who have been selected for the training camp.

Robertson is seeking to become the first person to win the World Series, World Baseball Classic and an Olympic gold medal.

There are 14 pitchers among the 28, including Homer Bailey, who threw two MLB no-hitters back in 2012 and 2013, and 21-year-old lefty Matthew Liberatore.

Boston Red Sox top prospect Triston Casas, a first baseman, is also among the group.

Nick Allen, Brandon Dickson, Jarren Duran, Tim Federowicz, Eric Filia, Logan Forsythe, Anthony Gose, Jon Jay, DJ Johnson, Mark Kolozsvary, Trevor Lane, Drew Parrish, David Robertson, Joe Ryan, Marc Rzepczynski, Luke Williams, Simeon Woods Richardson and James Sherfy complete the squad.

The US face Nicaragua in their opening game in a week's time, while the Dominican Republic and Puerto Rico also join them in Group A.

The group's top two will advance to the super round, and one team from the Americas will qualify for Tokyo 2020.

Second and third will advance to a last-chance global qualifier in Mexico.

Hosts Japan, Beijing 2008 champions South Korea, Israel and Mexico have already secured their Olympic spots.