Becoming a champion in the UFC is no easy task. It takes years and years of total dedication and hard work, the reality being very few MMA fighters will wear UFC gold in their entire careers. There are many great fighters who have not had the pleasure.An EPIC welterweight matchup set for 5️⃣ rounds! [ #UFC263 June 12 on ESPN+ PPV ] pic.twitter.com/xlxa6xroHk— UFC (@ufc) May 26, 2021Once that dream has been realized though, there is an even harder task - holding on to it. No fighter in history wants to be a flash in the pan, merely keeping the belt warm for someone who can handle the pressure of being champion of the world. Once at the top, there is only one way to go.Let’s have a look at three UFC champions likely to lose the title by the end of the year.Aljamain SterlingUFC 259 Blachowicz v Adesanya: Weigh-InsThe only fighter in UFC history to win a championship title by disqualification, Aljamain Sterling is currently king of the bantamweights- although not exactly by merit. During the fourth round of his title fight against then champion Petr Yan at UFC 259, Sterling suffered an inexplicable illegal knee from the Russian while his own knee was still on the canvas.Demetrious Johnson on the Petr Yan vs. Aljamain Sterling fight 💀 pic.twitter.com/EDpckL2oYn— Borrachinha Depot (@FullContactMTWF) April 4, 2021Prior to his surprise victory, Sterling was essentially in survival mode, and the American had been completely outclassed by Yan in all four rounds. Whilst a rematch with Yan has not yet been officially announced, it will likely happen within the next four months, and it will certainly be Aljamain Sterling’s toughest test in the octagon to date - there are not many things scarier than a Russian looking for revenge, just ask James Bond.Charles OliveiraUFC 262: Charles Oliveira v Michael ChandlerCurrently, the man of the moment, newly crowned lightweight champion Charles ‘Do Bronx’ Oliveira is on a nine-fight win-streak in the UFC. His amazing comeback against Michael Chandler at UFC 262 showed all of his doubters what Brazilian resilience looks like.#PaiTaOnManda ai... https://t.co/xsejpfJ43n— Charles Oliveira (@CharlesDoBronxs) May 26, 2021However, the lightweight division is amongst the most competitive weight classes in the UFC- not everyone will prove as resilient as former unbeaten champion Khabib Nurmagodmedov.With the winner of the Dustin Poirier vs Conor McGregor trilogy likely to face ‘Do Bronx’ before 2021 draws to a close, the Brazilian will have his work cut out for him trying to hold on to UFC gold.Israel AdesanyaUFC 259: Blachowicz v Adesanya‘The Last Stylebender’ Israel Adesanya has had an unusual 2021 so far. The New Zealander ambitiously moved up to the light heavyweight division at UFC 259 earlier this year, only to be beaten by champion Jan Blachowicz - his first loss inside the octagon. Preparing for a UFC fight after a loss will be something Adesanya has never experienced before.YEET!! https://t.co/eCLgzYEHiF— Israel Adesanya (@stylebender) May 24, 2021On 12 June, the Last Stylebender returns to middleweight- where he is unbeaten- in a rematch against ‘The Italian Dream’ Marvin Vettori at UFC 263. Vettori arguably gave Adesanya his biggest challenge in the octagon at middleweight, dominating the third round with an impressive ground game.Adesanya’s loss to Blachowicz at UFC 259 was further proof that his ground game has not improved since the first Vettori fight- the blueprint is there- if Vettori can get him on the ground early in the fight then it will be a long five rounds for ‘The Last Stylebender’.