The Major League Baseball Players Association is investigating whether Jay Z might have violated the union's agent regulations for giving Robinson Cano a $33,900 watch during a recent birthday party for the New York Yankees second baseman in Belgium, sources told ESPN.com.

According to media reports and postings on Cano's Instagram account, Cano received a limited-edition Shawn Carter Classic Fusion watch by Hublot during an Oct. 22 party in conjunction with his 31st birthday. Jay Z, who helped to design the watch, performed in concert in Antwerp, Belgium, the previous night as part of his "Magna Carta Tour.''

Cano, a five-time All-Star and the biggest name in this winter's free agent class, left Scott Boras' agency in April to sign on with Carter (aka Jay Z). The music industry superstar became certified to represent NBA and MLB players earlier this year and he and his Roc Nation sports group have a burgeoning roster of clients that includes Cano, Oklahoma City Thunder forward Kevin Durant, WNBA star Skylar Diggins and NFL players Victor Cruz and Geno Smith. Ron Berkowitz, a spokesman for Jay Z, did not respond to an email or a text message Tuesday seeking comment.

Cano is represented dually by Creative Artists Agency, which will handle the bulk of his upcoming free agent negotiations, and Roc Nation. A baseball source confirmed to ESPN.com that Cano is seeking a 10-year, $310 million contract from the Yankees, who gave him a one-year, $14.1 million qualifying offer before baseball's Monday deadline.

Section 5(B)(5)(a) of the Players Association regulations states: "No Player Agent or Applicant shall provide, cause to be provided or promise to provide, any money or any other thing of value to any player, or any person related to or associated with such player, the purpose of which is to induce or encourage such player to use or continue to use any person's or firm's services as a Player Agent, Representative, or Draft Advisor.''

There is a clause allowing certain gifts if the player was already a client of the agent; however, any gift exceeding $500 must be disclosed to the union in writing. Players Association officials say the seven paragraphs of rules are meant to ensure that players choose their representatives on merit rather than what the union calls "improper inducements.''

Sources said that the Players Association has interviewed several of the principals and that Jay Z could be subject to unspecified discipline if he is found in violation.

Hublot, the Swiss luxury watch maker, plans to unveil 100 of the 18k yellow gold watches to the public on Nov. 20 at Barney's in New York.