The result was a 136-run stand with Dhawan, who hit 70 off 50 balls and a 15-run win which keeps Hyderabad equal top with the Mumbai Indians and Kolkata Knight Riders.
After 16 balls, Williamson had made 13. Then he took off.
From the seventh to 15th overs, Williamson struck 65 off 31 balls at a strike rate of 210.
His innings strike rate was 174.5, easily his best in the IPL. He scored 72 percent of his runs on the leg side.
And should you be thinking Williamson has suddenly donned a technicolour coat and stepped away from the modus operandi which has put him among the very best batsmen across the three forms, think again.
Indian star spinner Ravi Ashwin tweeted his admiration for Williamson's innings.
Williamson joined the Sunrisers in 2015 but has had lean pickings in terms of appearances, with just two that year, six last season, so today was his ninth match. But he made it count.
He won't do that every game but it should have opened the minds of the Sunrisers' management to what he can add to their title defence.
Only one team, the now-suspended Chennai Super Kings, have managed back-to-back titles, in 2010-2011.
With Indian swing bowler Bhuvneshwar Kumar the leading wicket taker with 15 at just 9.1 apiece, the Sunrisers are travelling well, and Williamson might yet come to be seen as the final piece in their puzzle.
■ New Zealand seamer Tim Southee has picked up a deal with Middlesex for English cricket's domestic T20 competition.
Southee will join Middlesex in early July after the Champions Trophy in England, and is expected to be available for 13 of 14 games, and the playoffs if Middlesex make it.
He will form a triumvirate of New Zealanders there, with Brendon McCullum to captain Middlesex in the competition and Dan Vettori the coach.
