Arman Tsarukyan entered UFC 331’s lightweight co-main event against Mauricio Ruffy as the top-ranked contender seeking to reestablish title-shot momentum after multiple prior cancellations and a long layoff. Ruffy, riding recent knockout wins and known for dangerous stand-up power, tested Tsarukyan early with a stiff right hand that caused visible swelling under the eye and briefly staggered the favorite. The bout shifted decisively in the final seconds of round one when Tsarukyan reversed position along the cage and landed consecutive elbows that produced the stoppage at 4:56. Post-fight, Tsarukyan immediately signaled for a championship opportunity while Ruffy later attributed the finish to his own defensive lapse under pressure. These in-fight developments and the emphatic nature of the ending shaped commentary around resilience, striking exchanges, and lightweight title implications.