More than 17 minutes of stoppage time was played in a frantic second half after Guangzhou goal-keeper Zeng Cheng was involved in a sickening collision with one of his own players.
Play was halted for more than 13 minutes as the gloveman received treatment on the pitch following a nasty head clash.
He was eventually stretchered off with what was believed to be a fractured cheekbone and serious concussion.
Up until that point it seemed Goulart’s goals – either side of Iacopo La Rocca’s second half equalizer – would be enough to give Guangzhou a comfortable win.
But the Wanderers mustered one-last effort, pulling a goal back in the third minute of injury time through Romeo Castelen to whip Parramatta Stadium into a frenzy.
With still more than 13 minutes left they pushed for another with substitute Kerem Bulut hving the best chance to snatch a draw soon after but he shot straight at Li Shuai.
There was no sign of the drama to come in a fairly subdued first half, with Goulart opening the scoring just before the midway point.
Mei Fang’s right-wing cross was nodded back across the face of goal by Elkeson, the ball eventually rolling into the path of Goulart who lashed it into the net with the aid of a deflection of Wanderers skipper Nikolai Topor-Stanley.
Despite plenty of endeavor the contest was devoid of many genuine chances as both teams defences were dominating.
Goulart almost doubled the lead on 33 minutes with a classy half-volley which drew a stunning reflex save from Ante Covic.
Labinot Haliti was looking the liveliest for the Wanderers but their best chance of the first half came right near the end, Topor-Stanley’s glancing header floating inches wide of the post.
Chasing the game the Wanderers lifted the intensity after the break and got their reward 11 minutes into the second half.
Nikita Rukavytsya’s corners were dangerous all night and it was no surprise that was the avenue for the equaliser.
No Guangzhou defender tracked La Rocca’s run to the near post, the Italian rising well and flicking on a header which went in off the far post.
But the jubilation of the Wanderers players and their fans lasted just two minutes before Goulart struck again, expertly tucking home Gao Lin’s cross at the near post.
It was that combination again which unlocked the Wanderers defence just six minutes later as Goulart completed his treble before Castelen’s response set up a thrilling climax.
Western Sydney Wanderers FC 2 (La Rocca 56’, Castelen 90+3’)
Guangzhou Evergrande 3 (Goulart 19’, 58’, 64’)
Crowd: 11,418 @ Parramatta Stadium