UFC's Arman Tsarukyan Headbutts Dan Hooker In Wild Weigh-In Altercation

Arman Tsarukyan is taking his fight against Dan Hooker head-on -- literally -- 'cause he butted his opponent right in the noggin during a tense weigh-in altercation.

There's some serious beef between these two guys leading up to UFC Fight Night in Qatar -- Tsarukyan wasted no time going after Hooker after joining the promotion ... and it only intensified in the days leading up to the bout.

The two came face-to-face on Friday ... and as they approached each other on the stage, Tsarukyan (22-3) jolted forward and made contact with Hooker's face.

The fighters were then separated ... but that didn't stop them from jawing at each other as they were held back.

In case you don't know the lore with these dudes, Hooker (24-12) went OFF on Tsarukyan in an interview with MMA Fighting this week ... calling the matchup "the working man vs. Richie Rich" -- a clear shot at his opponent's upbringing and resources due to his father's successful construction business.

"I feel like I'm a fighter for the working man and represent hard working and sticking at it and getting things out and accomplishing what you want through that," Hooker told the outlet.

"I feel like he's had everything handed to him. The best coaches and the best training and fly around here and just kind of had the easy road."

He didn't mince his words at all ... even referring to Tsarukyan as a mouthy little rich p***y."