The band played an old video from their concerts, and when it came Zayn's turn to pop up on the screen - Cardiff fans BOOED
Remaining bandmates Louis, Niall, Harry and Liam performed in Cardiff, and when they showed their fans an old concert video - Zayn's part in it did NOT go down well.
As the camera spanned each of their faces, there were loud cheers for all of the singer, but as it turned to Zayn's face at the end, the crowd erupted in boos.
Fans have shared the clip on social media, and one user wrote: "OH MY GOD THE 1D CROWD IN CARDIFF BOOED WHEN ZAYN CAME ON THE SCREEN."
Another added: "Fans booed Zayn during You&I advertise ."
Ouch.
Zayn fans were quick to hit out at Cardiff supporters after watching the series of clips, as one wrote: "i hate cardiff i still can't believe yall booed zayn."
Another wrote: "I LITERALLY HATE EVERY PERSON WHO WAS THERE AT THE OTRA CARDIFF AND BOOED ZAYN I HATE YOU."
Uhoh - serious split in Directioners here.
There was a whole lot of love for the rest of the band tonight, as they took to the stage with their biggest hits - and it sounded great by the looks of more clips online.
Excitement was sparked on Twitter recently when the mysterious hashtag #WelcomeBackTo1DZayn went viral.
Nothing official was announced so we think it's just a hoax that has turned into a frenzy amongst fans.
Watch the shock boos above, and see the four remaining singer performing in our snaps below: