The 21-year-old had never gone past six rounds before Hrgovic defeat and his corner should have adapted strategy

The end, when it came for Moses Itauma, was as shocking as it was worrying. Late on Saturday night, moving into the championship rounds of his first world heavyweight title fight, the 21‑year‑old had dictated the pace and dazzled Filip Hrgovic with his speed and skill. The 34‑year‑old Croat admitted that he believed Itauma had won each of the first eight rounds. And yet, in the fateful ninth, Itauma stumbled and weaved across the ring like a dazed and drunken kid. He looked lost and utterly spent.

Exhaustion had reduced him to the point where, as the experienced Hrgovic tore into him, Itauma also resembled a rag doll on the ropes. With the final two punches Hrgovic sunk a right into Itauma’s sagging body before nailing him with a pulverising left cross. It was so clearly over in that desolate moment that three things happened almost simultaneously.

• Promoter Warren confirms Briton recovering in hospital

• Croat accepts he lost first eight rounds before victory

Moses Itauma has been urged “not to give up” by Filip Hrgovic, the new IBF world heavyweight champion, who stopped the 21-year-old Briton with a dramatic and stunning turnaround in their title fight late on Saturday night at London’s O₂ Arena.

Itauma was taken to hospital in a precautionary measure after the fight and Frank Warren, his promoter, confirmed to the Guardian on Sunday morning that his young heavyweight was still under medical observation.

• 21-year-old Itauma stopped after ninth-round rally

• 34-year-old Hrgovic is first Croat to win such a title

• Cameron outpoints Mayer to unify 154lb titles

Moses Itauma’s hopes of becoming the second-youngest world heavyweight champion in history lay in ruins after the extraordinarily tough and resilient Filip Hrgovic stopped him in the ninth round of their IBF title fight. Yet, until the latter stages of round eight, the sheer speed and dextrous power of the Briton had dominated the contest, with the Croat being dropped in the second and caught again and again by jolting combinations.

The fight changed course when Itauma’s stamina suddenly dipped and he began to weave in woozy fatigue as Hrgovic fought back with granite-like determination. Itauma could not withstand the dark storm rolling over him in the ninth and he sank back against the ropes as Hrgovic opened up with renewed conviction. Just as the referee stepped in to stop the fight, Ben Davison, Itauma’s trainer, also sent a white towel sailing sadly over the listing ropes to save his man from a knockout.

Filip Hrgovic singing to the press is a stark contrast to the brooding Briton who is grappling with the blinding lights of fame and glory

Moses Itauma and Filip Hrgovic have presented an intriguing study in contrast this week. The 21-year-old prodigy from Chatham in Kent, of Slovakian and Nigerian descent, has been a thoughtful and slightly brooding presence while the seasoned 34-year-old from Croatia has been full of sunshine and songs.

On Tuesday, Hrgovic burst into a room where a few boxing writers sat and, looking tanned without a shirt beneath his leather gilet, belted out a word-perfect version of Saturday Night at the Movies, a 1965 ditty by the Drifters.