Chris Martin fell through his stage at the “Speed of Sound” … stepping backward while performing with Coldplay in Australia — and falling straight through a trapdoor onstage.

The singer-songwriter hopped onstage with the band for the fourth and final Melbourne date on their “Music of the Spheres” tour … and, he should’ve kept his eyes on the ground ’cause he stepped in the wrong spot and almost took a nasty tumble.

Watch the video … Martin’s reading out signs he sees in the crowd in between songs when he steps backward and falls — thankfully, into the waiting arms of a crewmember — who stops him from smacking into the harsh floor.

The crowd reacts with a bunch of gasps … but, Martin bounces up pretty quick — jokingly telling fans that wasn’t planned and thanking the stagehand for making the grab.

As always, the show must go on … and CM gets right back into the performance — so, seems he didn’t sustain any sort of injury.

Martin isn’t the first star to fall through a trapdoor … just last month, Olivia Rodrigo did the same thing in Melbourne — albeit, at a different arena. She was also uninjured and ended up performing her full show after.

Coldplay’s finished in Melbourne … but, they’ve got performances in Sydney and Auckland, New Zealand coming up this week.