Just 13 minutes after coming on as a substitute, the defender found the net from just inside his own half at the MCG before Jai Ingham netted a late equaliser for the home side.
The draw meant that the game would be decided by a penalty shootout and a miss from Stefano Padovan proved decisive as Melbourne claimed a surprise win.
The home team competed well during the opening stages of the game but it was Juventus who were showing the greater composure on the ball, with the best effort of the opening quarter coming through a free kick from Paulo Dybala, who came within inches of finding the top corner.
The Italian giants went even closer to taking the lead shortly after the half-hour mark when a cross found Daniele Rugani inside the penalty area, but his low effort struck the woodwork before the ball went behind for a goal kick.
Both teams made numerous substitutions at the break and it did not take long for one of Massimiliano Allegri's replacements to break the deadlock in sensational style with Blanco driving the ball over Lawrence Thomas's head from just inside the Melbourne half.
Despite the opener, the two sides continued to push men forward with Juventus attacker Padovan almost finding the bottom corner with a shot from outside the box.
However, moments later, Melbourne equalised through Ingham, who received the ball from George Howard before directing the ball into the bottom corner from 14 yards out.
After neither side could find a winning goal, the match would be decided from 12 yards and after both teams missed one of their first four penalties, Padovan saw his effort saved by Thomas.