Derrick Lewis set a new UFC heavyweight record with his 11th career knockout, taking out Aleksei Oleinik of Russia just 21 seconds into the second round on Saturday night at the main event of UFC Fight Night in Las Vegas.

Six seconds into the round, Lewis (24-7) leapt forward and landed a flying knee to Oleinik's head before following immediately with a hard right that dropped his opponent to the mat. Oleinik tried to protect himself but could not, with the fight called after a hail of punches.

Lewis, 35, has 19 knockouts in his career overall, though this was his first since October 2018. He won his third straight fight after taking the previous two via decision.

Oleinik (59-14-1) had a chance to win the bout in Round 1, getting a deep chokehold on Lewis but was unable to hold it long enough.

"It feels good," Lewis said of the historic victory. "Especially after ... the head submission he had on me, he had it pretty deep."

The highlight of the earlier fights came in the first main-card bout, where Iran's Beneil Dariush (19-4-1) knocked out Scott Holtzman (14-4) with a perfect spinning back fist late in Round 1.

Dariush feigned a right jab, spun to his left and landed the back of his left forearm squarely on Holtzman's face, dropping him immediately and requiring no further punches to finish it.

In other main-card fights, Chris Weidman (15-5) earned a unanimous-decision victory (29-27, 29-27, 29-28) over Russia's Omari Akhmedov (20-5-1) in a middleweight bout; England's Darren Stewart (12-5) submitted fellow middleweight Maki Pitolo (13-6) via guillotine choke at 3:41 of Round 1; and Russia's Yana Kunitskaya (13-5) won a unanimous decision (30-26, 30-27, 30-27) over Lithuania's Julija Stoliarenko (9-5-1) in a women's bantamweight fight.