The Reds boss admits the pair face a spell on the sidelines, with Pogba being hurt in training with France, while away for the recent World Cup qualifiers.
Varane was also initially injured during a stint with Les Bleus but briefly returned to the fold, only to suffer a separate issue, a hamstring strain, during the Champions League tie at Atalanta.
In an exclusive interview with club media's Stewart Gardner at Carrington, the manager was able to provide more detail on the two World Cup winners, who will be absent when United travel to Vicarage Road for Saturday's 15:00 GMT kick-off against Watford.