SINGAPORE - MMA fans may not get the rematch they had been eagerly waiting for after Brazilian challenger Luis Santos failed to meet the stipulated weight for his bout against One Championship welterweight world champion Ben Askren.

While the American was right on the limit at 169.5 pounds at Thursday's weigh-in at Bugis+, his opponent was over the allowance of 170 pounds, coming in at 172 pounds.

Despite the two-hour window allowed to shed the extra weight, the South American jiu-jitsu specialist was unsuccessful.

The duo's previous fight in the Philippines in April ended in a no-contest after Askren accidentally poked his opponent in the eye.

Askren, 31, took to Twitter to vent his frustrations last night: "So sick of amateur Jabronis that refuse to honor the contract put in front of them."

Prior to the dramatic turn of events, Santos had said via a translator: "I can't wait to get into the cage with him again. He didn't fight fair in the last match and I'm going to show him who's the better fighter."

Compatriot Yago Bryan, who was seeking to wrest Thai Dejdamrong Sor Amnuaysirichoke's strawweight crown, also failed to make the 115 pounds (52.2kg) limit ahead of the One Championship's Pride of Lions nine-bout card on Friday.

Bryan weighed in at 116.5 pounds while Dejdamrong came in at 114.5 pounds.

That clash at the Singapore Indoor Stadium will proceed but is no longer a championship fight.