The NCAA has come down hard on fantasy leagues, banning their advertising and sending a letter to DraftKings and FanDuel requesting that they stop running fantasy contests involving college sports, MediaDailyNews reports.

The sports organization “banned all sponsorship/advertising activity in televised college sports championships for DraftKings and FanDuel — which have exploded this NFL season with seemingly wall-to-wall advertising on TV networks,” the story reports.

This is big news in particular for the NCAA Men’s Basketball Tournament, which is set to air in March on CBS and Turner Broadcasting cable networks.

The NCAA said in a letter to the two fantasy league operators: “As we have communicated to you previously, since your games meet the definition of sports wagering within our bylaws, the NCAA will not allow advertising of your products in connection with NCAA championships, including television broadcasts.”

The report notes that it is undetermined whether the new college football playoff, which is not overseen by the NCAA and has a 12-year, $7.3 billion deal with ESPN, will take similar action.