Williamson and Indian opener Shikhar Dhawan shared a Hyderabad record stand of 176 for the second wicket against Delhi Daredevils to set up a nine-wicket win with seven balls to spare in Delhi. Hyderabad are the first side to qualify for the playoffs and have won nine of their 11 games under Williamson's leadership.
The result also meant Williamson's New Zealand team mates Trent Boult and Colin Munro are out of playoff contention, with Delhi the first franchise to be out of playoff contention.
Delhi made 187 for five, based around a brilliant unbeaten 128 by Rishabh Pant, the highest T20 score by an Indian, off only 63 balls including seven sixes.
However after the early loss of England batsman Alex Hales, Williamson and Dhawan went to town.
Dhawan got man of the match for his unbeaten 92 off 50 balls while Williamson finished on 83 off 53 balls, the innings highlighted by his trademark working the ball into the gaps as well as a couple of sixes.
Boult had a day to forget, having 43 runs taken off his 3.5 overs while Munro has lost his place in the side. Williamson hit three boundaries off his Northern Districts teammate including the winning runs.
The New Zealand captain has taken his aggregate for the IPL to an impressive 493, over 200 runs ahead of his next best Hyderabad teammate, at an average of 61.62.
Hyderabad's next game is away to the other in-form team, the Chennai Super Kings on Sunday night. Chennai are second on 14 points, four behind Hyderabad.
