A major upset
The Romanian was in the zone from the start, breaking her 37-year-old opponent in the first game before holding to love as she moved the most successful tennis player of the Open era all over court with perfect tennis.
Whatever Williams threw at her, Halep always had the answer, and at times it seemed she was seeing the little yellow ball like a football.
With Halep leading 5-2, Williams handed her opponent a set point with a volley error and lost the set after a loose forehand return off a body serve.
Was Halep about to pull off a major upset?
After a winning volley in the opening game of the second set, Williams let out an almighty roar, usually the sign she would stage one of her legendary comebacks.
But any hopes Williams had of turning the match around were dashed at 2-2, when she was broken once again.
Another break followed, and suddenly Halep found herself serving for the title at 5-2. After setting up three match points, Williams dumped a forehand in the net and Halep sunk to her knees, holding her arms aloft.