Justin Gaethje’s coach has highlighted a ‘big mistake’ Ilia Topuria made that allowed his man to triumph at UFC White House.Gaethje put a beatdown on Topuria to become the new UFC lightweight champion this past weekend, but had to overcome extreme adversity to do so.Topuria dropped Gaethje with a series of body shots in the second roundGettyThe former champion opted to stay on the ground to try and submit Gaethje – a huge error in the eyes of Trevor WittmanGettyIn the second round of the main event clash, ‘El Matador’ was punishing Gaethje with nasty body shots while finding huge success with his left hook straight to the liver.Topuria proceeded to land successive shots right on the money with just over two minutes to go in the second round, forcing a wincing Gaethje to flop to the canvas.The previously undefeated champion quickly mounted Gaethje on the canvas before attempting various submissions.But the American defended well, looking relieved to have caught some much-needed breath on the canvas.That, in the eyes of head coach Trevor Wittman, was a crucial turning point in the headliner that allowed Gaethje to catch a second wind and go on to claim the win, as well as a remarkable $825,000 in bonus money.Topuria’s big mistake“Overcoming the body shot, I think Ilia made a big mistake there,” Wittman explained to Daniel Cormier, who was calling the fight alongside Joe Rogan and Jon Anik on the night.“I think that was a big mistake on Ilia’s part, going to the ground, because Justin was really hurt.“And Justin’s just a durable guy. He’s very smart in situations. He knows when to take breaks.“There were times in the fight, like in the third and the fourth round, where I was like, ‘Stop taking breaks, you’ve got to fight!’“But it’s easier said than done.”Gaethje was a massive underdog to get the job done in Washington DC – but defied the odds once againGettyTopuria was left beaten and bruised, suffering the first defeat of his 18-fight professional careerGettySpeaking on his team’s mission, Wittman added: “The game plan was to use our footwork, use the open foot to dig outside.“Also, use left angles when we’re coming into pressure, just because when he starts going back, it was dangerous.“Like, very dangerous. If you open up like this, he’s very good at opening the shoulder and finding hooks.“So the game plan was to pull him in, not use low kicks in the beginning, [but use] high kicks and things like that just to make him respect [Gaethje’s power], and try to kick his power hand.”Gaethje followed the game plan to a tee, slowly opening up with his jab to wear down Topuria and eventually make him quit.Wittman knew that when Topuria tired, he would straighten his back on the defence, which would allow Gaethje to pepper him continuously, as he did, with his snappy jab.After a close call at the end of round three, ‘The Highlight’ got the job done after the fourth, when Topuria’s brother, fellow UFC fighter and cornerman Aleksandre Topuria, signalled to referee Marc Goddard to stop the fight.UFC ScheduleFor all the upcoming fights and results this year, check out talkSPORT.com’s UFC schedule.