When Sampras eventually beat Patrick Rafter after four sets of high-quality tennis, the darkness had begun to fall.

BBC: Sampras' legacy already in place

Crest will fall on trough, and the result will be darkness.

ECONOMIST: Microscopy

Short-sellers tend to move under cover of darkness, launching stealthy guerrilla raids on stocks they deem ready for a fall.

FORBES: Short Story

When prices fall, the bulb will dim and the country could be plunged back into darkness.

ECONOMIST: Russia's economy