Throughout the history of mixed martial arts, extraordinary fighters have come along that have made fans wonder what their ceiling is and whether or not they have what it takes to be the best in their division.RELATED: The Anderson Silva Leg Break (& 9 More Of The Scariest Injuries In MMA History)However, for some of these fighters, injuries plagued their career, and fans' questions about how great they could be, are forced to go unanswered. For some of these fighters, they were forced to retire from the cage before reaching their potential, and for some fighters, their reigns on top of the division did not go as planned. Overall, some fighters like Cain Velasquez were able to make an impression on the sport, but fans are forced to wonder how great they could have been.

10 Cain Velasquez

At one time, former UFC Heavyweight Champion Cain Velasquez appeared to be the greatest heavyweight fighter to ever step into the octagon. Injuries appeared to play a major role both times Velasquez lost his UFC title. After winning the UFC title in 2010 by defeating Brock Lesnar, an injury kept Velasquez from defending the title for over a year. When he did defend the title, he lost to Junior dos Santos. Velasquez managed to stay healthy for two years. He won back the title and defended it twice before an injury kept him out of the cage for about 18 months. Upon his return, he lost his title to Fabricio Werdum.

Velasquez was never able to stay healthy following his title loss. It took over a year for him to return after the loss to Werdum. After his 2016 win over Travis Browne, it was two and a half years until he had his final fight, with was a loss to Francis Ngannou.

9 Brock Lesnar

In 2008, former UFC Heavyweight Champion Brock Lesnar took the UFC by storm. Within his first three fights, Lesnar managed to win the title and become the division’s biggest star.

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Lesnar’s strength and wrestling ability made him a threat to any UFC heavyweight. However, Lesnar’s struggles with diverticulitis hindered his MMA career. Lesnar’s struggles with the illness began in 2009 and resulted in him only being able to fight once that year. Following losing his title to Cain Velasquez in 2010, the illness returned, and he was unable to fight for over a year. He returned in a losing effort to Alistair Overeem and went back to professional wrestling a few months following the loss.

8 TJ Grant

Following an impressive five-fight win streak in the UFC lightweight division, TJ Grant had earned the opportunity to fight for the championship. However, injuries kept Grant’s championship dreams from ever coming to fruition.

Following his fifth consecutive win, a knockout win over former title contender Gray Maynard, Grant was granted a title opportunity against Benson Henderson. Grant suffered an injury and was replaced by Anthony Pettis, who went on to win the title. Grant was then given a fight against Pettis, but an injury once again forced Grant to withdraw. In the end, Grant would never get his title shot and would retire from the sport.

7 Travis Lutter

Travis Lutter made a name for himself by winning The Ultimate Fighter and receiving a fight against former UFC Middleweight Champion Anderson Silva when he was champion.

By winning The Ultimate Fighter, Lutter was granted a title opportunity but failed to make weight. He still received a fight against Silva but was submitted by the dominant champion. In his next fight, Lutter was knocked out by Rich Franklin and was released from the promotion. Outside the UFC, Lutter would only fight twice before being forced to retire. In 2010, Lutter was knocked out by Rafael Natal. In his final fight, Lutter suffered a neck injury and never fought again.

6 Cyborg Santos

Evangelista “Cyborg” Santos, the former husband of Cris Cyborg, career was forced to come to an end following one of the most devastating knockouts in MMA history.

After competing in the sport for almost twenty years, Santos’ career came to an end after suffering a fractured skull due to a flying knee by Michael “Venom” Page at a Bellator event in 2016. Prior to the injury, Santos’ career was highlighted by stints in PRIDE and Strikeforce.

5 Shane Carwin

Injuries began to plague the career of former UFC Interim Heavyweight Champion Shane Carwin at the peak of his career. Carwin was unstoppable at the start of his MMA career. He suffered his first injury setback after winning his first 11 fights, which all ended with a knockout or submission. Following a win over Gabriel Gonzaga, it took Carwin over a year before he fought Mir for the interim UFC title.

Carwin suffered his first loss in a title unification fight against Brock Lesnar. It would be almost a year before Carwin would fight again. In his next fight, he lost to Junior dos Santos. His loss to Dos Santos would be the last of his career. He was scheduled to fight Roy Nelson, but injuries forced him to withdraw. He later retired from the sport.

4 Michael Bisping

Eye injuries ultimately led to the end of former UFC Middleweight Champion Michael Bisping’s career. In 2013, Bisping suffered a detached retina in a fight against Vitor Belfort. Despite the injury and knockout loss, Bisping bounced back from the loss and eventually won the UFC title in 2016.

Throughout his career, Bisping was one of the most active fighters on the UFC roster. As a result, he may have not given his body enough time to recover. Just a few weeks after losing his UFC title to Georges St-Pierre, Bisping took a fight against Kelvin Gastelum. Bisping lost the fight by knockout and started having issues with his one eye that was not injured. As a result of the injury, Bisping retired from the sport.

3 Robert Whittaker

In 2017, Robert Whittaker reached the pinnacle of the sport when he won the UFC Middleweight Championship. However, his title reign was plagued by injuries.

RELATED: 10 Injuries That Cancelled MMA Fights At The Last Minute

Whittaker won an interim title by defeating Yoel Romero. He was promoted to undisputed champion after Georges St-Pierre retired and relinquished the title. Due to injury, it would be almost a year before Whittaker fought again, earning another victory over Romero. It would be 21 months until he defended his title. In 2019, Whittaker lost his title to Israel Adesanya. Since losing the title, Whittaker has managed to stay healthy and active but has not been able to regain his title.

2 Khabib Nurmagomedov

Former UFC Lightweight Champion Khabib Nurmagomedov is one of the most dominant fighters to ever step into the octagon. However, injuries kept him from being active during his UFC tenure. In 2020, Nurmagomedov retired from the sport as champion. While he retired from the sport with 29 wins and no losses, only 13 of his fights happened in the UFC. Nurmagomedov was in the UFC for almost nine years and only fought 13 times. At one point, Nurmagomedov was injured for two full years following his impressive win against former UFC Lightweight Champion Rafael dos Anjos.

While his legendary career features wins against Conor McGregor, Dustin Poirier, and Justin Gaethje, it is interesting to think what could have been if Nurmagovmedov did not suffer so many injuries.

1 Dominick Cruz

Former UFC Bantamweight Champion Dominick Cruz is the poster boy for fighters whose careers are devastated by injuries. For almost seven years, Dominick Cruz fought actively and was one of the best pound-for-pound fighters in the world. During this time, he won 19 fights and earned the WEC and UFC Bantamweight Championship. Following his fourth title defense, an injury forced Cruz to relinquish his title and he did not fight for almost three years.

In his return, Cruz earned a victory against Takeya Mizugaki. Following the win, injuries would force Cruz to sit out another 16 months before he would fight again. Cruz did manage to fight three times in 2016, but following a loss to Cody Garbrandt, it would be another three and a half years before he would fight again. Cruz fought two times last year but is yet to fight in 2022.