Melvin Guillard's tenuous history relationship with World Series of Fighting continues.

The UFC veteran was pulled from the WSOF 20 card Monday, because he was not able to present his medicals to the organization in a timely fashion, WSOF president Ray Sefo confirmed with MMAFighting.com. Guillard was scheduled to meet Ozzy Dugulubgov in the co-main event of WSOF 20, which is scheduled for Friday night at Foxwoods Resort Casino in Connecticut.

MMAjunkie was the first to report the story.

Sefo said that communication between Guillard and WSOF has been extremely limited and Guillard did not provide the adequate documentation to give to the commission in time for the fight. Guillard also refused to do any media through WSOF public relations, but slammed the promotion in other interviews.

"His management can advise him, can tell him what needs to happen," Sefo said. "At the end of the day, he's the professional fighter. He has to go get his medical, he has to do the PR. That's what it says in his contract. These are the obligations to the organization he's with. The unprofessionalism just continues. He's left me no choice but to pull him from the card."

Guillard missed weight before what was supposed to be a lightweight title shot against Justin Gaethje last November. He also missed weight in his WSOF debut against Gesias Cavalcante last July. Guillard is still angry with WSOF that he had to forfeit 50 percent of his purse from the Gaethje fight, because he wasn't able to hit 155 pounds. Guillard came in at 159.

"It's funny, they never answer their phone when I need to talk to them, but yet when they want me to do interviews and they want something from me, they want to try and force me to do it," Guillard said on Submission Radio last week. "So there's a lot of things in the company that I'm not happy about and I'm the type of person [that] I'm always going to speak my mind and there's already other places that want to sign me. So I'm gonna go in this fight next week, I'm going to fight my ass off. I'm going to win this fight impressively so that way I have options, I have choices. You know because ultimately I'm going back to the UFC anyway.

"I'm going to let them know how I feel, for when you fuck over Melvin Guillard and not give him what he asked for after he swallows his pride, and takes a fight, and lets them take 50 percent; and I still fight for them, I still give them a good show [in] that last fight, even though I didn't make weight and fight for the title; but yet the fact that [WSOF executive vice president] Ali [Abdel Aziz] didn't man up and follow his promise, you know right now it's a little bit personal to me."

On the other hand, WSOF still believes it did Guillard a favor by keeping him in a catchweight fight against Gaethje since Gaethje, the champion, losing in such a bout would be a disaster for the promotion.

"That was even risky for us to let him fight Justin Gaethje as a non-title fight, but we allowed it to happen," Sefo said.

Sefo said a decision has not been made yet on Guillard's future with WSOF. Abdel Aziz told MMAFighting.com that he still has two more fights left on his contract.

Guillard did not respond to a request for comment from MMAFighting.com on Monday afternoon. An email sent to Guillard's manager, Abe Kawa of First Round Management, was not immediately returned.

Guillard, 32, fought in the UFC from 2005 to 2014, earning notable wins over the likes of Jeremy Stephens, Gleison Tibau and Dennis Siver. For a time, Guillard (32-14-2, 2 NC) was considered one of the best lightweights in the world. He was cut by the UFC after a loss to Michael Johnson last March.

Before the Gaethje fight, Guillard also aired dirty laundry between him and WSOF. This is just the latest in the saga.

Luis Montoya will step in and face Dugulubgov. A fight between Nick Newell and Joe Condon will be the new co-main event. WSOF 20 is headlined by a light heavyweight tournament semifinal between middleweight champion David Branch and Ronny Markes and will air live on NBC Sports Network.

"We're four days away from the fight," Sefo said. "He's got to weigh in three days from now and he doesn't have a medical. It's completely ridiculous."