Allardyce fears his squad being unsettled by transfer rumours.
"We can't be distracted by the January transfer window," he said. "We can't have players reading the paper thinking he might be sold, or he might come in or someone might be after them, because it is not going to happen.
"If we lose our focus, we lose our stability and if we begin to lose that we will struggle in the Premier League. If we struggle when we are going into the biggest two games this season, in the semi finals, then we won't get through, we won't win it.
"We have to stay focused and make sure in December, we get the results we need and that boosts the confidence and then we look forward to the semi finals.
"We can't look forward to the semi finals if we are down in the bottom three region and worried about our Premier League status. We have to make sure it is not like that when we get there."