From Longman Dictionary of Contemporary Englishfear the worstfear the worstEXPECTto think that the worst possible thing has happened or might happen When Tom heard about the accident he immediately feared the worst. → fear
Examples from the Corpus
fear the worst• Fearing the worst, police have called in reinforcements to help control the crowds.• After I hadn't heard from him for several hours, I began to fear the worst.• I knew I was being irrational but I began to fear the worst.• Only then did we begin to fear the worst.• Rumours about impending changes will occur anyway, and staff not fully informed are likely to fear the worst.• Then they called police and stayed up all night -- fearing the worst.• Rescuers feared the worst for the men trapped in the mine.• Mind you, I feared the worst for this year's crop of pantomimes. 