LAS VEGAS – UFC president Dana White was having an enjoyable dinner at StripSteak inside the Mandalay Bay casino, cautiously optimistic that Saturday’s UFC 200 was progressing without significant problems. Then his phone rang.

Jon Jones, the best pound-for-pound fighter in the world and part of UFC 200’s main event, had a June test with a potential performance-enhancing drug issue, according to the United States Anti-Doping Agency. Just like that, Jones would need to be pulled from the card, his light heavyweight title fight with Daniel Cormier done.

“Boom,” White said.

Boom indeed.

“Sucks,” White said.

That, too. For the UFC, which had built the finest mixed martial arts card of all time for its historic show. For fans, specifically the ones who had already bought the pay-per-view in anticipation of the Jones-Cormier main event.

UFC 200 will still feature two title fights and the main event is now a Brock Lesnar-Mark Hunt bout, but this is a loss.

And mostly for Jones, who has proven again as unreliable as he is talented, subverting his feel-good comeback from recreational drug issues. His descent had supposedly bottomed out with a 2015 hit-and-run accident that caused the UFC to strip him of his title and suspend him from the promotion. Now there is this.

He has fought just once in 18 months and spent Wednesday’s news conference trash-talking Cormier while predicting a return to dominance.

Jones has the right to demand a secondary sample be tested and should be afforded due process. However, with the result coming back so close to the card, and thus no time for the retest, there was nothing the UFC could do but pull him.

If he’s found guilty, he could face a two-year suspension from fighting that may forever derail his once-dominant career. And that doesn’t even factor in Jones’ potential legal problems.

“Can’t be good,” White said of how it would affect Jones’ probation. “Can’t be good.”

White arrived at a hastily called evening news conference at the MGM Grand looking solemn, hands stuffed in his blue jeans, using gallows humor to soften the blow. This hurt though. Professionally, for sure, as the loss of Jones-Cormier and their explosive rivalry was sure to help drive pay-per-view sales to an expected all-time high. That the card is still strong is about the only solace.

“If a fight of this magnitude falls off, at least it’s the biggest, baddest card we’ve ever had,” White said, seemingly trying to convince himself. “I guess if it’s going to happen …”

Maybe more notably this hurts personally. White trusted Jones with 200, trusted that he could avoid the trouble that has plagued him and bring this baby home.

Jones boasts a 22-1 record, the only loss from disqualification by elbows all the way back in 2009. He’s as good as MMA has ever seen, an overwhelming fighter, but he has struggled to put his partying days behind him. He has proven moody, erratic and spent too much time feuding with fans.

White reinstated him last fall after six months out of action. When Jones defeated Ovince Saint Preux in April, appearing sober and nearly his old self, White made him the headliner for 200. It was a replacement for what was supposed to be a Conor McGregor-Nate Diaz rematch that was cancelled only because McGregor refused to fulfill UFC promotional responsibilities.

Then Jones betrayed White’s trust and blew up everything.

“It’s always something,” White told Yahoo Sports on Wednesday. “This thing is like a baby, you can’t leave a baby alone for five seconds.”

Who knows if Jones will ever get his act together. The storyline this week was of redemption and he had plenty of people fooled. He was performing community service, said he had been staying clean and was fulfilling the terms of his 18-month supervised probation. He was sharp and even gregarious at his news conference earlier Wednesday. When he and Cormier were stood up for cameras after, he kept telling Cormier to “shut your mouth.”

He seemed eager to regain his belt and get on with his life. He looked in typically phenomenal shape. White began believing the legal troubles and suspension may have been the best thing to happen to the 28-year-old, a chance to reboot his life and career before it was too late.

“This is weird to say [but Jones seemed] like a completely different person,” White said.

The test result is almost assuredly for performance-enhancing drugs and not recreational, which can cause a fighter to be banned from competition only if it’s still in their system within a day or two of the fight. The Jones test took place on June 18. In 2014, a test three-plus weeks before a fight came up with a metabolite of cocaine in it, but it was out of his system later that month and thus he was allowed to compete. White says he had no idea why it took so long for news of the test to get to the UFC, but this was almost certainly PEDs, not cocaine or anything else.

The company handed all drug testing over to USADA in an effort to clean up the sport and take these decisions out of its hands. It sounds great in theory. So does the idea of stopping a dirty fighter from injuring a clean one.

“This is the way it should be,” White said. “We have the best program in all of sports.”

He wasn’t happy though. He was scrambling to figure out if the UFC could find a replacement on two days’ notice for Cormier, who was significantly disappointed to see his much anticipated rematch with Jones, and a major payday, fall apart.

“This one stings,” Cormier said. “This one isn’t an easy one to deal with.”

It was all happening so quickly. UFC matchmaker Joe Silva was in the air traveling back to Vegas when the news broke. When he turned on his cell phone upon landing, he was already inundated with fighters volunteering to take on Cormier, so time will tell if anything comes together.

First though, Silva tried to figure out what happened, why he was getting such offers. He texted White and Lorenzo Fertitta, one of the UFC’s owners.

“What the [expletive] happened?” Silva texted.

“Welcome to Las Vegas,” Fertitta texted back.

“What the [expletive],” White said, reading the texts and laughing at the absurdity of a once-tranquil night gone wrong.

That was the closest thing to levity he provided. His main event was gone. His historic card had the top cut off of it. A three-round fight featuring Lesnar –a great draw, but he spent the past four and a half years in professional wrestling – was now the finale.

The most heated and anticipated fight, a rivalry in the making, was finished. Arguably the best fighter the promotion had ever seen now was facing a lengthy suspension and a massive issue of trust from the promotion, fans and fellow fighters alike.

Jonny “Bones” Jones had stuck it to him again, stuck it to himself, also, a self-sabotage that no one can explain or understand.

“What are you going to do?” White said before looking at the incoming texts before heading toward the door. “I’ve got to get to work.”

He never finished that steak dinner.