West Brom have blocked tickets sold via exchange site Viagogo for the game against Manchester United on May 19.
The fixture will be the last game of Alex Ferguson's tenure at United and many tickets for the home end at The Hawthorns sold via the site have ended up in the hands of visiting supporters.
Ordinarily, the system is used as a way of allowing fans with season tickets to sell their seat for games when they cannot attend but, such is the attraction of attending Ferguson's last game in charge, West Brom have had to put a ban in place.
Any tickets sold after 08:00 GMT on May 8 will not be honoured and a West Brom spokesperson said the decision had been made with the safety of fans in mind.
"With Manchester United's help, we have identified that the vast majority of these orders were lodged by United season ticket holders/members," they said.
"This [block] is in keeping with all terms and conditions which stipulate that the club reserves the right not to honour orders from buyers that are suspected to be opposition fans.
"The safety of fans is paramount, which is why we so vehemently uphold the rules regarding the segregation of supporters.
"The club are working closely with the local authorities to limit the potential for away fans to obtain tickets in the home sections.
"We are monitoring all potential platforms where there is the potential for tickets to fall into the wrong hands."
The fixture, as well as being Ferguson's last, will be his 1,500th game in charge of United.