Artur Beterbiev defeated Dmitry Bivol by the narrowest of margins on Saturday night in Saudi Arabia.
With a majority decision victory, Beterbiev becomes the first undisputed light-heavyweight champion since 2002.
It was a battle where the differences were razor-thin, with both Russians hurt in an electric seventh round and enjoying success through the 12 rounds.
One judge had it a 114-114 draw, with the remaining two gave 39-year-old Beterbiev victory, just – 115-113 and 116-112.
The three judges at ringside were American Glenn Feldman, Spain’s Manuel Oliver Palomo and Pawel Kardyni of Poland.
After the fight, the judges scorecards revealed they were split on just two occasions – the fourth and seventh rounds.
All the judges gave Bivol, 33, the first two rounds, eighth and the ninth round, while they were unanimous on Beterbiev winning the third, fifth, sixth, 10th, 11th and final round.
None of those at ringside scored a round evenly or beyond the 10-9 margin, which would usually only be exceeded because of a knockout.
Bivol’s promoter Eddie Hearn was very unhappy with the scorecards, branding one of the judges’ card as “disgusting”.
But beaten fighter Bivol said he had no issue with the scoring, saying: “I don’t like excuses. I didn’t win and that’s it.”