On Friday the two men weighed in for the contest and both made weight.
On the scales the champion was the lighter man weighing in at 111lbs, a full 1lb inside the divisional limit, whilst Casimero was 112lbs, dead on the limit.
For the Thai this was a lb lighter than he was in his most recent bout, a decision win against Zou Shiming, but 1½lbs heavier than he was in his previous bout in Thailand, a split decision win against McWilliams Arroyo. Strangely he had appeared to struggle to make weight for his very first defense, against Kazuto Ioka.
As for Casimero this is the same weight he was last time out and 1¾lbs lighter than he was when he lost the IBF Light Flyweight title on the scales, in May 2014.
At the weigh in both looked in incredible shape and both seemed to have prepared very well for tomorrow's bout which can be seen live on Mono 29 in Thailand.
Amnat Ruenroeng looks to add another big scalp to resume as he faces Johnriel Casimero
(Image courtesy of thairec.com)