UFC Vegas 68 was headlined by a heavyweight clash between feared KO artist Derrick Lewis and surging contender Serghei Spivac. A win was pivotal for Lewis, who had dropped three of his past four while Spivac entered the first UFC main-event of his career on a two-fight win streak.Spivac managed to score an early takedown and went on to land some significant damage on 'The Black Beast' who once again looked at his wits' end on the ground. While Lewis got back up on his feet for a short while, 'The Polar Bear' lost no time in dragging him back to the canvas.After throwing Lewis all around the cage in a lopsided affair, Spivac sunk in an arm triangle and forced a quick tap at 3:11 of Round 1.Watch the highlights below:MMA mania@mmamaniaSerghei Spivac submits Derrick Lewis in the first round9513Serghei Spivac submits Derrick Lewis in the first round https://t.co/eAIZQjcd45The co-main event at UFC Vegas 68 featured a light heavyweight clash between Devin Clark and Da Woon Jung. While Jung went toe-to-toe against Clark for 15 minutes, the former RFA champ effectively outwrestled him to earn a unanimous decision win.UFC@ufcUnanimous for @BrownBearC! He gets back in the win column at #UFCVegas6818616Unanimous for @BrownBearC! He gets back in the win column at #UFCVegas68 https://t.co/ElZUPKymLKMarcin Tybura earned a comfortable unanimous decision win over fellow veteran Blagoy Ivanov in another heavyweight affair.UFC@ufcUnanimous for @MarcinTybura! He makes it 2 in a row with the W at #UFCVegas68 32130Unanimous for @MarcinTybura! He makes it 2 in a row with the W at #UFCVegas68 👏 https://t.co/KH0cebaN1sFeatherweight prospects Choi Doo-ho and Kyle Nelson fought to a closely contested majority draw.UFC@ufcThe Korean Super Boy and Kyle Nelson fight to a majority draw at #UFCVegas68How'd you score it?[ Live now on @ESPNPlus ]57446The Korean Super Boy and Kyle Nelson fight to a majority draw at #UFCVegas68How'd you score it?[ Live now on @ESPNPlus ] https://t.co/MscW2InB4aUFC Fight Night: Lewis vs. Spivac full card resultsMain cardSerghei Spivac def. Derrick Lewis via submission (arm-triangle choke) (3:05 of Round 1) Devin Clark def. Da Un Jung via unanimous decision (30-27, 30-27, 30-27)Marcin Tybura def. Blagoy Ivanov via unanimous decision (30-27, 29-28, 29-28)Doo Ho Choi vs. Kyle Nelson ruled a majority draw (29-27, 28-28, 28-28)Adam Fugitt def. Yusaku Kinoshita via TKO (ground and pound) (4:36 of Round 1)Preliminary cardAnshul Jubli def. Jeka Saragih via TKO (ground and pound) (3:44 of Round 2)Jeong Yeong Lee def. Yi Zha via split decision (29-28, 27-30, 29-28)Rinya Nakamura def. Toshiomi Kazama via KO (punch) (0:33 of Round 1)Hyun Sung Park def. Seung Guk Choi via submission (rear-naked choke) at 3:11 of Round 3Jun Yong Park def. Denis Tiuliulin via technical submission (rear-naked choke) (4:05 of Round 1)Tatsuro Taira def. Jesus Santos Aguilar via submission (triangle armbar) (4:20 of Round 1)Note: The Ji Yeon Kim vs. Mandy Bohm fight has been canceled.