Rosé and Bruno Mars’ “APT.” is one of the best pop songs in recent memory. You know it, I know it, and Coldplay know it. It’s why the galactic-scale pop-rock band welcomed the Blackpink alum to join them a few hours ago at Goyang Stadium in Goyang-si, South Korea. After Chris Martin sat at the piano and played a bit of “APT.” solo, the full band kicked in and Rosé burst onto the stage. She did her parts, and Martin filled in for Mars (as much as Chris Martin could be expected to fill in for Bruno Mars — very different flavors of cheese there). When the song was over, they ran it back a second time.