Tickets are getting pretty tough to come by for this week’s colossal B1G-ACC Challenge matchup between Michigan State and Duke, two of the premier programs in college basketball. And if you’re looking to buy, you may want to be a little extra cautious.

According to Chris Solari of the Detroit Free Press, Michigan State University has already learned of counterfeit tickets being sold for Tuesday night’s showdown on Craigslist, as well as other sites. MSU says that, if fans intend to purchase tickets that way, the tickets should be validated through the Spartan Ticket Office.

Duke is ranked No. 10 and Michigan State No. 11 in the latest college basketball associated press poll. The Blue Devils are 7-1 on the season while the Spartans are 5-2. Both are expected to be Final Four contenders.

Monday night begins the annual tradition of the B1G-ACC Challenge, where all 14 teams from both leagues meet on the hardwood. The Duke-Michigan State matchup is one of the marquee games in the series.

Duke and Michigan State tip off at 9:30 p.m. ET with coverage on ESPN on Tuesday, Dec. 3.