The Waveriders levelled the score just before the hooter for the third quarter and then shifted the momentum their way by scoring two quick goals in the last quarter to hand the Magicians another humiliating defeat.
It was Mumbai who sounded the board first when Sandeep Singh converted a penalty corner in the eight minute.
The Waveriders got even when an unmarked Oskar Deecke smashed a pass from Akashdeep Singh into the goal.
In the second quarter, Norris Jones scored a brilliant field goal to leave the Mumbai goalkeeper gasping for breath.
Three goals in the span of two quarters saw the Magicians replacing Rao with PR Sreejesh and the move immediately paid off as the latter made some breathtaking saves.
Though Sandeep's drag-flick could have gone wide, Glenn Turner deflected it into the goal to reduce the margin to 2-3.
Jason Wilson scored the equaliser for the home team before Sandeep converted a short corner for a 4-3 lead.
The lead was short-lived as Gurvinder Singh Chandi passed to a diving Akashdeep and the latter deflected the ball in.
From there on, Delhi were unstoppable.