Nikita Tszyu Stops Oscar Diaz in Sixth Round, Claims WBO Regional Title

Nikita Tszyu defeated previously undefeated Oscar Diaz by TKO in the sixth round of their super-welterweight bout in Newcastle on Wednesday, capturing the vacant WBO International Super Welterweight Title and extending a remarkable family record on Australian soil.

The Details

The contest, held at the Tszyu-Castle Entertainment Centre, was stopped between rounds after Diaz could not continue following a knockdown in round six. According to ABC News, Tszyu dropped Diaz with a heavy left hand in round two and landed sustained body shots throughout the fight. In round six, Diaz went down to a knee after heavy blows to the body. Nine.com.au reported that Tszyu landed two additional punches after Diaz had taken a knee, prompting protests from the Spanish corner. The referee reached a nine-count before Diaz rose, and the bout continued to the end of the round. Diaz's corner then informed the referee their fighter could not continue.

The late punches drew post-fight commentary. Tszyu, quoted by Nine.com.au, said: "I mean, it was just a split-second reaction. I didn't see that his knee was on the ground. I saw him bent over. In my experience, if they're bent over then keep punching." Diaz entered the bout with a 16-0 record, marking his first professional loss.

Tszyu also reflected on his approach, telling Sporting News Australia: "I landed some really solid shots on his forehead and was surprised he was able to take some of them. We had to start working the body and we got there in the end."

With the win, the Tszyu family record in Australian home bouts extends to a combined 54-0, including Kostya Tszyu (18-0), Tim Tszyu (23-0), and Nikita Tszyu (13-0), according to ABC News.

Context

The fight comes four months after Tszyu's January 2026 bout against Michael Zerafa ended controversially when Zerafa claimed he could not see, leading to a stoppage. The Tszyu camp has sought to move beyond that result with a clear statement against Diaz, who held a top-15 ranking.

Boxing commentator Peter Badel, quoted by Nine.com.au, said of the performance: "For the first time, I now believe Nikita can be the whole package. I never thought he would be the fighter that he is... On this performance, Nikita has graduated from domestic slugger to international contender. He is the real deal."

Fellow Australian boxer Liam Paro also weighed in, quoted by Nine.com.au: "That's a huge win. That proves he's at the world level taking out a top 15 world contender... He was a lot more composed and a lot more balanced. It was what we needed to see."

Tszyu is currently ranked sixth with the IBF and is projected to climb as high as third in the super-welterweight division, though the ranking update is not yet official. KeiThurman and Tony Harrison have been discussed as potential next opponents, with Harrison having been knocked out by Tim Tszyu in 2023.

What's Next

Tszyu dismissed an immediate leap to world title contention, telling Nine.com.au: "I'm not really there yet with confidence. I still consider myself a novice and I think I have a lot more to learn before I go for the world titles. They'll come with discipline and consistency and hard work, growth is inevitable."

Options for his next outing include Keith Thurman and Tony Harrison. The timing and opponent for his next bout have not been confirmed.