Beware of critiquing the reigning champion.

Before being eliminated from “Survivor 49” following a tribe switch, Matt Williams took a shot at two-time victor Sandra Diaz-Twine, expressing his disdain for her renowned “anyone but me” approach.

When Williams’ remark sparked an online frenzy among fans, Diaz-Twine, 51, caught wind of the controversy while vacationing in Hawaii and promptly responded to Williams, 52.

“All I’m gonna say is my strategy has paid off not once, but twice. You better ask somebody,” the “Survivor: Pearl Islands” and “Survivor: Heroes vs. Villains” winner wrote on Instagram.

In an exclusive chat with The Post, Williams revised his opinion on Diaz-Twine’s tactics.

“It’s so different when you’re out there,” the airport ramp agent said. “I’m sitting home watching on TV, I watch Sandra and I’m like, ‘How is that a strategy? How could anyone go play Survivor and your strategy is anyone but me?’”

“And then when you’re out there and your backs against the wall… Well, Nate [Moore] said, ‘You were throwing these guys under the bus.’ I said, ‘No, I wasn’t. I wasn’t campaigning against Jason [Treul] or against Sophi [Balerdi],’” Williams continued. “I just said, anyone but me. I thought prior to going out on the island those words will never come out of my mouth. And there I am. Anyone but me.”

Williams then bowed down as he walked back his comments about Diaz-Twine.

“I apologize, Sandra. You got it to work. You got it to work twice!” he said. “I couldn’t get it to work for one tribal. So you know something I don’t, Sandra.”

And while Williams hasn’t seen the online fan reaction to his remarks about Diaz-Twine, he did hear about her epic clapback.

“Somebody told me she was in Hawaii when she heard,” Williams said. “So yes, Sandra, you are the queen. I’m eating crow.“

Williams also told The Post that he feels screwed by the tribe swap that took him out of the game.

“You got to get lucky a couple of times to win this game. And that was the opposite of getting lucky,” he said. “Yeah, I looked around at the buff everybody had, and I thought, ‘Oh, this this might not end well for me.’ Yeah, it was a bad swap. I was on the wrong end of things.“

“We all knew a shakeup was coming. But I didn’t sit down and think, ‘Well, this would be great and this would be bad,’” Williams continued. “I just thought, ‘Great, something’s about to happen.’ And all of a sudden, I thought, ‘Oh maybe this isn’t so exciting,’ when I looked at the makeup of the tribe.”

“Survivor” airs Wednesdays at 8 pm ET on CBS