From 2003 to , he spent parts of each season in Single-A ball for the Lansing Lugnuts and the Daytona Cubs, before moving on to Double-A in mid-2006. As a member of the Lugnuts, Fox was given the opportunity to catch for then-Cubs pitcher Mark Prior, who was on a rehab assignment. He was ecstatic to catch for Prior, and even invited his family members to attend the game. However, upon arriving at the club house, he found out that Paul Bako was actually slated to catch the game. Fox approached his manager, Julio Garcia, who claimed that Fox was not experienced enough to catch a Major League pitcher like Prior. Garcia then revealed that the team was playing a practical joke on Fox, and that he would actually be in the team's lineup.