Midfielder Goodman Dlamini was the hero for Usuthu, scoring twice on the day, including an 87th-minute equaliser, as the hosts twice came from behind.
Dlamini started the goal-glut as early as the sixth minute, scoring direct from a 25-yard free-kick after he had been fouled by Vasco skipper Keenin Lesch.
Usuthu’s lead lasted just 15 minutes, with Lesch equalising just before the midway point of the first half with a header. Sibusiso Zuma provided the assist with a well-weighted cross.
And the Cape side took the lead for the first time on 36 minutes when midfielder Zeka Karkee scored with a long-range shot that had the beating of AmaZulu goalkeeper Mbongeni Mzimela.
The score was 2-1 in favour of Vasco da Gama at half-time, and the visitors were probably worthy of their lead.
Ten minutes into the second half AmaZulu brought themselves level at 2-2. Aidan Jenniker brought down Muziwandile Khwela in the box and referee Harry Lekitlane pointed to the penalty spot. Lehlohonolo Majoro converted the spot kick.
But Vasco surged ahead again in the 72nd minute, with Jonathan Armogam further enhancing his reputation with a close range goal to make it 3-2 in favour of the visitors.
AmaZulu seemed set for their first defeat in six games but with just three minutes of regulation time remaining they drew level once again. Goodman Dlamini crashed home a shot from outside the penalty area to make it 3-3 and ensure a share of the spoils.
The result sees AmaZulu move up to ninth on 26 points, while Vasco have shifted up one place to 12th on 25 points.