The holding player shook off a hip problem to slam home an injury-time winner and secure his team top spot in the standings after the visitors had looked set to hold out
The brilliant Brattan goal from well outside the area was a fitting end to a high-quality contest highlighted by some sweet passing football from Brisbane and a dogged, tactically astute performance from the Victory.
The hosts created the better chances throughout the first versus second clash, but it looked like the Victory would hold on through sheer determination until deep into stoppage time, when Brattan collected a pass 25 metres from goal and fired his effort into the bottom left corner.
The three points earned for the Roar ensures they cannot be caught at the top of the table with three games remaining.
Playing centrally, Henrique was the first to test Victory goalkeeper Thomas in the 11th minute with a swerving shot from outside the area, which was parried clear, before Dimitri Petratos' follow-up shot was also saved.
Moments later, Liam Miller was presented with a tremendous chance when a Diogo Ferreira pass found him all alone in the area, but his effort was straight at Thomas, who nonetheless did well to block it.
A moment of Thomas Broich magic nearly set up the opener for the hosts, as he danced past his marker on the left before sending a cross to the back post, however it was the diminutive Henrique on the receiving end and he could not get enough contact on the ball to direct it into the net.
As Tom Rogic began to see more of the ball, the Victory worked their way into the game, and they could have gone ahead if not for a brilliant Michael Theo save.
Rogic played a through ball to Kosta Barbarouses, who cut it back from the byline for James Troisi to try a shot from close range, but the Brisbane keeper got his right foot to the ball to keep it out.
The Roar were still putting together some slick combinations in the attacking third, however, and it was Petratos who came close just before the break, sending a vicious shot just wide of the far post from the edge of the area.
After the half-time break, Brisbane continued to dominate possession but could not create anything clear-cut until just over the hour mark, with Miller playing in Henrique, whose attempt was tipped wide by an advancing Thomas.
Theo intervened to cut off one dangerous-looking Victory counter-attack when he came well out of his area to stop Barbarouses.
Henrique then scrambled for a rebound after Thomas fumbled a Jack Hingert strike, but could not beat the Victory keeper from close range.
Broich beat his man on the left and played a sideways pass to an open Miller, whose shot from distance floated just over the crossbar.
The German then ran at the Victory defence himself, sending a low effort just past the far post after racing into the box.
Brisbane's left-back Ferreira was the next to test the visiting keeper, forcing a tremendous save from Thomas following a weaving run forward.
Brattan's strike came two minutes into stoppage time to send the Suncorp Stadium crowd into raptures.
Brisbane Roar 1 (Brattan 90+2)
Melbourne Victory 0
Crowd: 17, 965 @Suncorp Stadium