It meant that the world champions' 100 per cent record also came to an end, having claimed back-to-back one-two finishes in Bahrain and Saudi Arabia to start the season.
Verstappen was in second when the issue occurred, following a brilliant sweeping overtake on the 26-year-old by Sainz on lap two.
It's unclear what caused Red Bull's brake issue, but the hot temperatures at the Albert Park Circuit caused multiple cars all kinds of trouble in terms of tyre degradation, with a flurry of early pit stops.
A dramatic moment was caught by the Sky F1 cameras in the pit lane, when Verstappen's rear brake seemed to explode, sprialling debris and smoke into the air.
What's more, it was clear to see the issue, with flames billowing from the world champion's RB20.