Saturday's lone fixture in the T20 World Cup saw New Zealand come out as victors against Sri Lanka by 65 runs.
With their 2nd victory of the tournament, New Zealand now sit comfortably on top of Group 1 with 5 points.
Choosing to bat first in Sydney, the Kiwis were put under some early pressure by the Lankan bowlers as they lost their openers Finn Allen and Devon Conway inside the first 3 overs.
Skipper Williamson also departed soon after but Glenn Phillips and Daryl Mitchell put together an 84-run partnership to help stabilise the innings.
While Mitchell fell for 22, Phillips took the Sri Lankan bowlers apart. The big-hitting Kiwi batter smashed his 2nd century for New Zealand and helped his side post 167 on the board.
In reply, Sri Lanka were bamboozled by Boult and Southee. Their top-order crumbled which saw the Islanders being reduced to 8/4 inside the first 4 overs.
Sri Lanka could just never recover from there. While captain Dasun Shanaka top-scored for the Lankans with a 35, Sri Lanka's failure to stitch together a good partnership saw them eventually fold for 102.
Trent Boult finished his brilliant spell with figures of 4/13 - his career-best record in T20Is. The Black Caps with the victory also opened a 2-point lead at the top of Group 1.