Ariana Grande was confronted by an unruly fan who leaped a barricade and grabbed her at the “Wicked: For Good” premiere in Singapore … and her costar Cynthia Erivo quickly jumped in to protect her!

It all went down Thursday … as Ariana, Cynthia, Michelle Yeoh and Jeff Goldblum were all hand-in-hand, greeting fans on the yellow carpet at Universal Studios Singapore.

Check out the video … as Ariana greets a fan, a man on the opposite side suddenly jumps the barricade and beelines straight for her — throwing his arm around her and jumping up and down with a big smile.

Needless to say … Ariana and Michelle both look shocked, but Cynthia wastes no time getting between the wild fan and Ariana — putting hands on his shoulders and forcing him off AG.

Security then steps in and removes the fan … as Cynthia and Michelle comfort Ariana.

As the man is carried off by security guards … he’s met with a chorus of boos from other fans. It appears the guy is known for these stunts … he’s believed to be an online personality called “Pyjama Man” who posts videos of himself bum-rushing performers onstage and goofing off in public on TikTok.