Porto have slapped a £40million price-tag on Manchester United and Manchester City target Eliaquim Mangala, according to the Daily Mail.
Manchester United have been heavily linked with the 22-year-old centre-back over the last couple of months.
Red Devils boss David Moyes and first-team coach Jimmy Lumsden both attended Porto's midweek Champions League encounter on Wednesday to make a personal check on the Frenchman.
Manchester City are also keeping a close eye on Mangala's progress but are unlikely to meet Porto's astronomical price-tag.
Manchester United boss Moyes will have money to spend in January, as the Premier League champions will be desperate to get their title bid back on track.
However both Manchester United and Manchester City are unlikely to meet Porto's demands over Mangala.