We might look back on this as the most difficult phase of all.
This is usually the most difficult phase for the dog.
He always talked to me as if I were a child going through a difficult phase.
"You must be having one of those difficult phases."
Now comes the most difficult phase: devising a strategy for change.
The project is entering a difficult new phase as more women become ill.
At the present stage the negotiations are in a difficult phase.
He is in a difficult phase of his life.
This was the most difficult and dangerous phase of the operation.
However, his departure would bring about a difficult phase in the club's history.