Usman Nurmagomedov dominated Benson Henderson as he earned a first-round submission win to defend his lightweight title at Bellator 292 in San Jose, California.
Nurmagomedov, 24, dropped Henderson with a high kick before finishing the fight with a rear-naked choke.
The win extends the unbeaten start to Nurmagomedov’s career to 17.
The Russian also advances to the semi-finals of Bellator’s Lightweight Grand Prix.
Following defeat, American Henderson, 39, announced his retirement following a distinguished 17-year career.
Henderson is a former UFC lightweight champion, winning the title in 2012, and closes his career with 30 wins from 42 bouts.
Nurmagomedov was making the first defence of the title he won from Patricky Pitbull in November where he became the youngest champion in Bellator history.
In victory, Nurmagomedov emulated his retired cousin and former UFC champion Khabib in winning a world title having never suffered defeat.
Henderson came into the fight on a two-fight win streak with his last victory coming against Ireland’s Peter Queally in September.
Early in the first round Nurmagomedov landed a spectacular question-mark kick which knocked Henderson to the ground.
Nurmagomedov immediately pounced on his stunned opponent as he looked to secure a finish on the canvas.
Despite resilience from Henderson, Nurmagomedov expertly worked towards back control where he was able to secure a rear-naked choke and end the fight.
Following victory, Nurmagomedov embraced Henderson and raised his arm in tribute to the veteran’s esteemed career.
“San Jose, I love you. I had some great moments in this building. I had some tough moments too but you always show up, thank you” Henderson said in the post-fight interview.
“I always told myself if I lose at all in my last four fights I signed with Bellator, and it’s about that time.
“I’ve had a nice long run, I was able to do a lot of amazing accomplishments. Thank you to everybody around the world, I appreciate that.”
Following the post-fight interviews, Henderson left the SAP Centre arena in tears as fans applauded him.
The Lightweight Grand Prix, featuring seven current and former champions in Nurmagomedov, Henderson, Pitbull, AJ McKee, Brent Primus, Mansour Barnaoui and Tofiq Musayev has been described by Bellator president Scott Coker as the “toughest tournament I’ve ever seen”.
Nurmagomedov will face the winner of Barnaoui and Primus, who meet in Paris on 12 May, in the semi-finals.
The evening’s other quarter-final saw Russia’s Alexandr Shabliy beat Azerbaijan’s Musayev following a front kick finish in the third round.
Shabliy, 29, will face American McKee or Brazil’s Pitbull in the final four.