WBO cruiserweight champion Oleksandr Usyk beat WBC title holder Mairis Briedis by a majority points decision to unify the belts.
The two met in the semi-final of the World Boxing Super Series tournament and Usyk won 115-113, 115-113 and 114-114 in Latvia.
He will now meet the winner of IBF champion Murat Gassiev against WBA belt holder Yunier Dorticos in the final.
2012 Olympic Champion, 30-year-old Usyk expressed before the tournament his desire to unify the belts in the cruiserweight division and to take home the Muhammad Ali Trophy. And he kicked off in style:
The Ukrainian went to Berlin in Germany on September 9 in the tournament opener and produced a spectacular display at the Max-Schmeling-Arena to stop former world champion Marco Huck in the 10th round.
“I do not care where I fight,” said Usyk, the tournament’s number one seed. “In Riga, there were 10,000 fans and that's great. The fans received a beautiful and interesting battle between two world champions.”
32-year-old Briedis excited an ecstatic hometown crowd at a sold-out Arena Riga on September 30 to score a unanimous decision in his quarter-final over the tough Cuban challenger Mike Perez.
The event will conclude in May and features a $50m prize fund.
That pool will be split across two tournaments, one for super-middleweights and one for cruiserweights, with each featuring eight fighters competing from a quarter-final stage.
Whoever wins the cruiserweight section will hold all four belts.
Usyk's hard-fought win over Briedis extended the 31-year-old's career record to 14 fights without defeat.