Australia and top spot on the domestic one-day cricket table.
Chasing 268 at the SCG, WA needed nine off the final over from Thornely, who hadn't bowled previously in the innings.
The medium pacer kept his nerve, despite being smashed for six by Bret Dorey off the penultimate delivery.
With two required off the final ball, Thornely had Dorey caught by Daniel Christian at deep backward square leg.
As the temperature nudged 40 degrees in mid-afternoon, Haddin first day-night match at the SCG in four summers.
set up a total of 267, despite the Blues losing their last seven wickets for 18 in just 30 balls.
one-day century, though it was his first at the SCG.
(49 off 48), who scorched eight well struck boundaries.
the WA bowlers.
losing wickets regularly.
When the mercury dropped dramatically during the evening, it was spinners Nathan Hauritz, (3-42 off 10) and Jason Krejza (3-41 off 10), who stepped up for NSW.
Stuart MacGill.
all-rounder Moises Henriques withdrew with a leg injury.
The Warriors needed 37 from the last five overs, but the their challenge.
balls, belting sixes off Nathan Bracken and Thornely.
