Pencil Neck - Big cats prefer to attack from behind, so a cougar vs Komodo dragon would likely have the cougar circling around and pouncing on the Komodo from behind and then biting its neck from there. There's a well known YouTube of a tiger doing the same thing when it was facing a croc. Also a Komodo the same weight as a cougar would be noticeably smaller in body because its tail is so long and thick and takes up a big percentage of its body weight.
Komodo Dragon gets one bite, and it's over.
The venom stops the blood from clotting, so the cougar starts to bleed out.
Rapid blood loss sends cougar into shock, triggering flight response -- only accelerating the blood loss.
Komodo Dragon has found it's dinner.
Also, the Komodo Dragon armor means it can weather a hell of a storm.
Cougar has to fight a flawless fight...
.. would be better off just buying the dragon a beer and live to fight another day.