Wales fans could outnumber their Bulgarian hosts as Gary Speed's men complete their failed Euro 2012 campaign in Sofia on Tuesday.
BBC football commentator Nigel Adderley reports: "The Bulgarian FA have said the fans have planned a boycott of tonight's match."
An estimated 400 Wales fans are heading to the 43,632 capacity stadium.
Bulgaria recently sacked coach Lothar Matthaus and could finish bottom of Group G if Wales win.
Wales can finish third in the group if they are victorious and Montenegro win in Switzerland.
Goalkeepers: Wayne Hennessey (Wolverhampton Wanderers), Boaz Myhill (West Bromwich Albion - on loan at Birmingham City)
Defenders: Darcy Blake (Cardiff City), Chris Gunter (Nottingham Forest), Adam Matthews (Celtic), Neil Taylor (Swansea City), Ashley Williams (Swansea City), Lewin Nyatanga (Bristol City)
Midfielders: Joe Allen (Swansea City), Gareth Bale (Tottenham Hotspur), Andrew Crofts (Norwich City), David Edwards (Wolverhampton Wanderers), Aaron Ramsey (Arsenal), David Vaughan (Sunderland), Jonathan Williams (Crystal Palace)
Forwards: Craig Bellamy (Liverpool), Hal Robson-Kanu, Simon Church (both Reading), Steve Morison (Norwich City), Sam Vokes (Wolverhampton Wanderers)
Stand-by list: Lewis Price (Crystal Palace), Neal Eardley (Blackpool), Ashley Richards (Swansea City), Rhoys Wiggins (Charlton Athletic), David Cotterill (Swansea City), Andy Dorman (Crystal Palace), Jermaine Easter (Crystal Palace), Ched Evans (Sheffield United)