Pestano and Cepeda each hit three-run homers in a nine-run seventh inning to lead Cuba to a win by the mercy rule. Gourriel hit a two-run homer in a five-run fourth and finished with four RBI's.
"Mexico and Cuba ... it was a tough game, we had to play to win it, but at the same time, we needed to keep our pitchers fresh because we were both thinking in the next round," Cuba manager Higinio Velez said.
Yulieski Gonzalez (1-0) got the win, giving up one hit with three strikeouts in two innings of relief for Cuba.
"Obviously I do not like to lose, much less like this, but we are in, we wanted to classify, we wanted to finish first, but we could not do it," Mexico manager Vinicio Castilla said. "You have to learn from your mistakes because the good teams will make you pay".
Mexico will open the second round on Sunday in San Diego against South Korea, winner of Group A in Tokyo, while Cuba will face Japan in a rematch of the 2006 WBC final won by Japan.
"In the next round we will play the Asian team, they have great pitching, and Mexico will be there also and they are going to be different," added Velez.
Mexico's Foro Sol, located 1.4 miles above sea level, proved to be a hitters delight, with 28 homers hit in the six games played here.