Open Guillermo was played by none other than Frederick Mannix (handicap +9) until his transfer to Polo Stud Schockemöhle in Germany. Canada‘s highest handicapped polo player has riddenw the stallion in the world‘s largest polo tournaments. Open Guillermo ran the Triple Corona, the Jockey Club Open 2015 including the final, the Palermo Open, the Queen‘s Cup and the Coronation Cup. Open Guillermo is a brother of the famous mare Open Guillermina by Nicolás Pieres (handicap +10). Open Guillermina was among other titles Best Playing Pony at the Palermo Open 2012 and the Hurlingham Open 2017. Open Guillermo‘s dam Open Geisha was played at the Palermo Open between 2004 and 2007 by Gonzalo Pieres (handicap +10) and Matías Mac Donough (handicap +8). In the finals of 2005 and 2006 the mare was played two Chukkers. Open Guillermo‘s father Ellerstina Chismoso is a full brother of Open Chimento, who has been played by Adolfo Cambiaso (handicap +10).