Lashley, who had to endure four opponent changes for his promotional debut with the Texas organization, won by keylock submission over Knothe (20-7) at three minutes and 44 seconds of the first round.
With the win, Lashley improved to 7-1 and is on a two-fight win streak since losing to Chad Griggs at a Strikeforce event in August 2010. Lashley has two more fights with Shark Fights.
In addition to the historic UFC on FOX event on Saturday, other MMA action took place over the weekend and we'll take a look at some notable fights after the jump.
-- PRIDE veteran Aleksander Emelianenko was knocked out in 23 seconds by Magomed Malikov (4-1) on Saturday in the main event of M-1 Challenge 28 in Russia. In his first punch of the fight, Malikov timed an overhand right to level Emelianenko against the ropes.
The setback put Emelianenko (17-5) in a position of back-to-back losses for the first time in his eight-year career.
Aleksander's older brother Fedor, 35, fights this Saturday against Jeff Monson in Moscow.
-- On Saturday, Douglas Lima earned a title shot against Bellator welterweight champion Ben Askren by stopping Ben Saunders in the second round with strikes at Bellator 57 in Rama, Ontario, Canada.
At the same Bellator event, Alexander Shlemenko won this season's Bellator middleweight tournament and will rematch Bellator champion Hector Lombard at a later date. Shlemenko on Saturday took a unanimous decision over Vitor Vianna.
-- UFC veteran Rich Clementi bounced back from his May loss to Shinya Aoki in DREAM by defeating Ronnie Rogers Saturday at a Victory Promotions event in Lowell, Mass. The 34-year-old Clementi won with a rear-naked choke in the second round.