The Rebels have never played finals in a full competition but have a maiden series in sight after scoring seven tries to four at AAMI Park on Saturday night to book their third successive win.
Five-eighth Carter Gordon bagged two tries, his combination with South African halfback Ryan Louwrens key to the crucial win while Melbourne's pack continued to dominate.
Lancaster may have the luxury of choosing between the Wallabies and the Olympics if he continues his trajectory, with the 20-year-old a stand-out in just his third Super game.
Sevens recruit Darby Lancaster races away against the Highlanders. (Rob Prezioso/AAP PHOTOS)
The Kempsey product signed a two-year deal with the Rebels but has a clause that allows him to play sevens in the Paris Games if selected, having been a regular member of the national team before switching to the 15-player game.
He scored the opening and closing tries of the first half to set up a 26-10 lead heading into the break, showing off his explosive pace and skills.
Lancaster grubbered ahead, beating star Highlanders fullback Jacob Ratumaitavuki-Kneepkens to the ball.
His second was equally impressive, bursting on to a tip-on pass from fullback Andrew Kellaway and racing to the line - although he appeared to knock-on when he released and regathered after a would-be tackle.
Carter Gordon (right) scored two tries and kept the Rebels ticking over against the Highlanders. (Rob Prezioso/AAP PHOTOS)
Melbourne's first-half haul included a penalty try when a pass to Lachie Anderson, who had a clear run to the line, was deliberately knocked-on by Ratumaitavuki-Kneepkens, who also got a yellow card.
Looking to break into the finals-bound top eight themselves, the Highlanders kept coming, halfback Folau Fakatava crossing in the 56th minute followed by Ricky Jackson 12 minutes later.
But Gordon's double, helped by the hard-running Kellaway and Louwrens, kept the Rebels on top.
Ethan de Groot scored for the Highlanders with six minutes remaining but Lancaster capped the win when he scooped up a loose ball and dashed 55 metres for his third of the night.
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