Ben Askren has not forgotten about his unfinished business with Luis 'Sapo' Santos, lifting the lid on the frustrations that have seen fights repeatedly fall by the wayside in ONE Championship.

Askren, one of the top welterweights in the fight game with a record of 15-0, will defend his title against Agilan Thani at ONE: Dynasty of Heroes on Friday 26 May) in Singapore, his first fight in over a year. It's a much-welcomed return to action; since leaving Bellator for Asia's biggest MMA promotion in 2013, the American has fought just four times.

In some circumstances, the periods of inactivity that sidelined the former US Olympian were out of everyone's hands.

His October 2016 meeting with middleweight champion Vitaly Bigdash was shelved following the death of the King of Thailand, Bhumibol Adulyadej, prompting a period of mourning across the country and forcing ONE to cancel their event.

Attempts to rearrange that fight fell through, however, with the Russian turning down the chance to hold the champion vs champion bout at a later date.

While the Bigdash spectacle frustrated Askren, it was nothing compared to what he felt with Santos. A highly-anticipated clash with the Brazilian at ONE's Valor of Champions was ruled a no contest after an accidental eye poke in April 2015.

A rematch was a no-brainer and plans were immediately put in place for it to take place the following November. A day before fight night, however, the welterweight title was taken off the table when the challenger missed weight by two pounds. Askren gave 'Sapo' the chance to fight anyway if he weighed in at less than 190lbs at a second weigh in. Santos turned those terms down.

Askren's attention is now firmly on Thani, the undefeated 21-year-old he will meet on Friday who the two-time NCAA champion says he already has far more respect for than 'Sapo' and Bigdash.

But the bad blood he shares with those two remains. Askren says both men "only have to say yes" if they want a shot at his title – and hopes calling them out again provokes the right response.

Speaking exclusively to IBTimes UK, the ONE welterweight champion said: "It's all about 'Sapo' and Bigdash. I have no idea why they said no but hopefully now that I have told people that they have said no so many times, I hope they feel totally embarrassed. They only have to say yes after this fight.

"If they don't say yes after I've told everyone they are sissies so many times, they just look stupid. How can your career have any validity when you refuse to fight somebody? It's not as if they are fighting someone below them, they are getting the opportunity to be the champion. That's a great opportunity for both of their careers. But the fact they have said no is mind blowing."

Ben Askren
Askren still feels the frustration of seeing two fights cancelled. Getty

Askren won his welterweight title at ONE: Reign of Champions in August 2014 after a TKO victory over Nobutatsu Suzuki. In addition to his frustrations with 'Sapo' and Bigdash, his last fight in 2016 against Nikolay Aleksakhin became a non-title affair when his opponent again failed to make weight. Overall, things could have gone smoother for him.

"When I left Bellator, I weighed up all my options and ONE was the best opportunity I had at the time. I was excited about it. They fought me twice in the first three months, it really took off quickly. It wasn't that long after the business with 'Sapo' where the wheels fell off a little bit."

Askren refers to the eye-poking incident that saw their first meeting end a no-contest. He has previously suggested his opponent was always looking for a way out of the fight from day one.

"The 'Sapo' fight ended up being a no contest because he's a moron and a liar. I was supposed to have the second 'Sapo' fight later that year, and then he's a moron and a liar again. I showed up twice to fight that year."

So is the Brazilian welterweight the biggest source of frustration he's come across in mixed martial arts? "That's fair to say. And now he won't even say yes, this is just so ridiculous its almost beyond comprehension for those of us who have a normal level of intelligence."

While he is one of ONE's household names, Askren's exposure has been limited having been left to stew in the longest periods of inactivity he's experienced in his fighting career.

"It wasn't really ONE's fault, they could have kept me busier, but I was moderately busy, but it was 'Sapo' that ruined my 2015. He's a freaking moron. And a liar. That's kind of where the wheels fell off and hopefully ONE are able to make up for a few of those missed fights this year."

Time to settle those beefs may be running out. The Milwaukee-native has previously suggested he would call time on his fighting career at the age of 30. Now, 32, he admits he is still "heading in that direction."

"This whole thing, it's taught me a lesson in patience," Askren said. "I've had to be patient for a while. It's been beyond my control, it wasn't my option, and it wasn't my choice. Some things in life are beyond your control and they were and I am just hoping that things change this year."