A battered and relieved Tyson Fury was awarded a controversial split-decision win over the remarkable Francis Ngannou, who was making his boxing debut, in Riyadh. One judge believed that Ngannou, who knocked Fury down heavily in the third round, had won the fight 95-94. A second had the exact same score in Fury’s favour while the third official’s scorecard was a ridiculous 96-93 margin for the WBC world champion. In this 10 round non-title fight Ngannou dented and then tarnished the champion’s prestige by fighting with fire and purpose.

Fury was badly swollen around the left eye and the possibility of his heavily hyped fight for the undisputed world heavyweight title against Oleksandr Usyk happening on 23 December, as planned, is now in jeopardy. The Ukrainian, who holds the IBF, WBA and WBO titles, stepped into the ring afterward to meet Fury and to make clear his readiness to fight on the agreed date. Fury suggested he was ready to rumble right there and then, but before Usyk climbed between the ropes, he had sounded less certain. His promoter, Frank Warren, then stressed that they will have to think carefully as less than two months does not offer Fury much time to recover from his bruising encounter with Ngannou.

Related: Tyson Fury beats Francis Ngannou by split decision after knockdown – live reaction

Fury has been boxing for 25 years, since he first walked into a gym at the age of 10, and his status as world heavyweight champion only skims the surface of his vast experience and ring knowhow. Ngannou, in contrast, had never boxed professionally before he climbed through the ropes and earned himself a cool $10m. But, as gracious as he was when hearing of his undeserved defeat, it felt as if he had been unlucky at the dead of night in Saudi Arabia.

Of course Ngannou is also a fighter to his very core and he carved out an impressive career in the brutal world of Mixed Martial Arts, which saw him become an admired UFC heavyweight champion. In the dramatic third round an overhead left caught Fury heavily on the temple and he tumbled to the canvas. Fury got up, as he does so often before in his career, but the composed and determined Ngannou surged with confidence.

Instead of a routine demonstration of prowess in the ring, Fury struggled for the rest of the fight to match a man who has endured many dark moments in and out of the MMA cage. But Ngannou’s composure stood out most of all on a dramatic night. As they entered the last three rounds both men were marked up and puffy around the eyes. Ngannou landed a long left as he maintained the pressure in the eighth round. He then hit Fury with a hard left and a clubbing series of combinations which buzzed the boxing champion, and left him looked ragged. It had been another big round for Ngannou.

Fury seemed flat and all out of ideas as a quiet and almost bewildered crowd watched the final two rounds. Weariness also took its toll and Fury did not attempt to force the pace. It was almost as if he believed that the judges would favour him and so he allowed his fate to be protected by their decision-making.

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Ngannou had admitted before the bout that he faced a mountainous challenge against Fury. But he also stressed that “I am not afraid of mountains – I have been climbing them all my life”. Born into poverty in a village in Cameroon, Ngannou had begun working in a quarry when he was just 10. Life was no easier when, aged 26 in 2012, he left for Paris in the vague hope that he might learn how to become a boxer. He was jailed briefly as a refugee before he found work as a nightclub bouncer who was also offered opportunities on France’s low-key MMA circuit. Ngannou showed extraordinary grit and determination and he earned himself a contract with the UFC in 2015.

He could have hit the jackpot in his boxing debut. For the dwindling band of purists and romantics who cling to the notion that boxing can still be a noble and uplifting sport this was another night tainted by contention. Usyk will have found great encouragement while watching Fury’s laboured performance – but it is now uncertain when the circus will be back in town, amid the darker shadows of Riyadh and boxing.