Leinier is a Cuban born super grandmaster, earning the title in 2001. He is a five-time Cuban Champion, earning the titles in 2002, 2003, 2006, 2012 and 2016. He competed in two FIDE World Championship, reaching the quarterfinals in 2004 where he lost to Teimour Radjabov in tiebreaks. He won the Capabalanca memorial for the first time the same year, and two more times after that in 2008 and 2009.
In 2013, he won the FIDE Grand Prix event in Thessaloniki ahead of the likes of Caruana, Nakamura and Topalov, earning 30 rating points. The following year, he reached his peak FIDE rating of 2768. His current rating of 2739 puts him in the top 20 list of the strongest players in the world. Leinier has represented Cuba on board one at the Olympiad for many years, earning a silver medal in the 2016 Olympiad in Baku. He is also a former World Blitz Champion, winning the title in 2013 in Kazakhstan.
Dominguez is a familiar face in Saint Louis, having participated in previous editions of the Champions Showdown as well as being a wildcard in the Saint Louis Rapid and Blitz. He was part of the team that assisted Fabiano Caruana during the 2018 Candidates tournament and the 2018 World Championship Match. He officially switched federations in December of 2018 and this event will be his first appearance under the US flag.