Multiple outlets report that doping testers detect traces of a banned bodybuilding substance in tests of eight Tunisia players at the World Cup in Mexico. The reports say the findings come from player drug testing during the tournament and that some affected players play club football in the UK. According to the accounts, the presence of the prohibited substance is attributed to possible contamination, with one claim linking it to contaminated meat. The reports describe the issue as part of Tunisia’s challenging World Cup campaign and note that the substance is considered banned under anti-doping rules. The coverage also references the broader context of World Cup match preparations, including concerns about food sources and personnel arrangements, but the central points across sources remain the same: eight players from Tunisia are reported to have tested positive for traces of a prohibited substance, and contamination is cited as the explanation. The articles do not, in the provided text, give additional specifics about the exact substance name, the testing authority, or the formal process that follows such findings.