Medina ended his long drought and spared Mexico's blushes when he scored on the hour, sliding the ball into an open net from a tight angle after the Senegal goalkeeper Khadim Ndiya fumbled possession.
It was Medina's first goal for his country since he scored against Jamaica, and gave his team their first win in three World Cup warm ups in front of a sold out crowd of 60,000.
Mexico, who play hosts South Africa in the opening game of the World Cup next month, were held to scoreless draws in their last two matches, against Iceland and Ecuador, raising concerns about their firepower up front.
Despite dominating the match with Senegal, who failed to qualify for the World Cup, those fears were intensified when Mexico squandered a string of chances before Medina, who came on early in the second half, finally broke the deadlock.
The Mexicans are in the United States on a three-match tour that began against Ecuador in New Jersey last Friday. They play their final match against Angola in Houston on Thursday.
Mexico are in Group A at the June 11-July 11 World Cup finals with the hosts, France and Uruguay.
