that scene you described is in lost in the cloud, cirrus is playing against chan-il who's bigger than him, so cirrus decides to trick chan-il and whisper something about chan-il's girlfriend, which makes chan-il flustered and lose focus so cirrus flips him and wins so he can look good in front of skylar.
OHHH do you remember the chapter? TGANK YOU SO MUCH EITHER WAY
yess it's from chapter 68-69 and no problem anytime <3
THABK YOUU <333
Now it might also be a scene that i warped in my head but it a BL manhwa as far as I remember, the setting was in a school place and it was a school festival going on? And the main characters were competing against each other in many different rounds and I think there was a round of ssireum too and one of them cheated at first but then the other whispered something which caused the other guy to lower his guard and so the mc won.
I thought it was Lost in the cloud, Checkmate and Semantic error but I don't remember the scene in any of them.
The artstyle/colour palette was similar to Lost in the Cloud too