HITC Sport understands that Fulham are unlikely to allow deal to happen without cover.
HITC Sport understands that Cauley Woodrow's injury means it is increasingly unlikely that Fulham will allow captain Ross McCormack to leave the club.
Fulham have made it clear they do not want to sell but were anticipating an offer, and sources close to the club have told HITC Sport that they felt it would be tough to fend off Boro.
However, that was before Woodrow suffered a badly broken foot on Saturday in Fulham's FA Cup defeat at Sheffield Wednesday.
Woodrow has since had surgery and HITC Sport understands that he is unlikely to play again this season.
McCormack's exit is made all the more complicated by the fact that Fulham are limited when it comes to signing a replacement as a Football League embargo means they could not spend any money from a potential deal - but could bring in free agents or loans - but options are limited during the January window.
Whilst Boro remain hugely keen on the former Leeds man, they might now have to turn to other targets.