Masvidal is no fan of Chiesa, as he showed in a media availability Thursday ahead of their fight on a televised card Saturday at KeyArena.
"As long as he keeps that beard out of my face, we'll be cool before the fight," Masvidal told reporters. "I'm going to tell the (athletic) commission (to) wrap that up. I don't want to get no mat herpes or nothing on my face.
"I've been in this game a long time, got nothing on my face and I ain't about to catch some syphilis or whatever he's got going on in that beard. I'm just going to make sure we keep the distance and pop him."
Chiesa (9-0), who won Season 15 of "The Ultimate Fighter," is known for his beard. Ironically the bushy growth came about because producers of the reality TV show wouldn't left him trim his beard during filming.
"'Can't do it,'" he recalled them telling him. "'Consistency. You trim it, we can't go back and use old footage.'"
"So I got stuck growing this huge burly beard. The fans fell in love with it and I kind of got accustomed to it. So now it's just kind of part of who I am."
He trims the beard after each fight, keeping a smaller version before growing it again for the next tussle.
"Any time I shave it off, I feel like I look a pinhead," he said.
Masvidal, a 28-year-old from Miami, accused Chiesa of being "kind of a jerk" in his last fight, which was a submission win over Masvidal teammate Anton Kuivanen.
"My teammate, he's like a real standup dude, real sportsmanlike and he (Chiesa) wasn't very sportsmanlike towards him," said Masvidal.
"I just think he's a punk and I'm going to go out there and prove it," he added.
Asked about the bad blood, Masvidal (24-7) stressed that it was not personal.
"It's not I'm going to see him in the street and fight him," he said. "It's not like he owes me money. I just don't like the dude. I just dislike him.
"Usually my opponents, I don't care if they win the lottery or they die. For this guy, I really don't care for him at all."
Still Masvidal says the ill-will serves as motivation for him.
"It definitely adds a little something to it," he said. "You want to get in that extra shot right before the referee stops it. Bang.
"It's a fun. It's a fight."
Chiesa, for his part, couldn't care less about Masvidal's comments.
"Whatever pumps him up, man," said the 25-year-old from Spokane, Wash. "I'll talk on Saturday night. I'll let my actions speak for themselves."
"I'm not a talker. I'm a performer," he added.