A TV show "Friends" co-stars share a moment.

Friends fans have been left feeling emotional over Matthew Perry crying in the trailer for the big reunion.

A full-length trailer for the Friends reunion episode, which will premiere in the US next Thursday (27 May), has been released, and it shows all six of the main cast members together for the first time since the show ended in 2004.

Jennifer Aniston, Courteney Cox, Lisa Kudrow, David Schwimmer, Matt LeBlanc and Perry are shown reminiscing about the sitcom while wandering around the character’s apartment sets and quizzing each other on plot lines.

Cast members from US sitcom "Friends" pose for a photograph.

It wasn’t all laughs, though – at one point, Perry can be seen getting emotional and, choked up, says: “Yep, I’m gonna cry now.”

Aniston can be seen placing a reassuring hand on his shoulder.

This moment had a strong effect on fans, leaving them feeling quite tearful themselves.

“I was emotionally distraught when he said he was going to cry in the trailer,” one person said, WITH ANOTHER fan adding: “When Matthew Perry was like about to cry I was bawling. He’s been through so much.”

Cast members, as they appear now, on the sets of the comedy series 'Friends'.

“I’m already crying but I SWEAR if we see Matthew Perry cry I’M GONNA LOSE IT AND JUST BREAK DOWN,” one person wrote.

Meanwhile another stated: “If Matthew Perry cries, then I will cry too!”

Perry has been open about his struggles while making the show. After becoming a household name as Chandler Bing in 1994, he became addicted to alcohol and prescription drugs and, in 2016, said that he “[can’t] remember three years” of the show as he was “a little out of it”.

The actor attended rehab twice during his run on Friends. He has since opened his own rehabilitation centre for alcoholics.