After arriving in Veracruz 24 hours late due to bad weather conditions, Alberto Espasandin's slightly unsettled side fell to an 87-72 defeat to Halcones Rojos.
Mauricio Aguiar top-scored for the home team with 30 points at the Benito Juarez gymnasium, while Fernando Martines netted 11 in a losing cause for the Mexicans.
In their second warm-up match, the visitors bounced back to destroy Angeles de Puebla 105-64 with Emilio Taboada pouring in 23 points and Esteban Batista adding 18.
For the home team, Carlton Holmes claimed 25 points in vain, while there were also 14 from Theo Powell.
On Saturday, Uruguay face Guadalajara's Los Tecos, before taking on Lechugones de Leon on Sunday.