Undefeated Australian Tim Tszyu scored a unanimous points decision over tenacious American Brian Mendoza Sunday to successfully defend his WBO super welterweight title for the first time.

The 28-year-old, son of renowned former world champion Kostya Tszyu, was brilliant and brutal in the 12-round battle on Australia’s Gold Coast that left Mendoza bloodied but somehow still standing.

All three judges scored the bout in Tszyu’s favour, 116-111, 116-112 and 117-111.

The early rounds were even before the fight burst to life in the seventh, with Mendoza taking a battering.

He was hurt again in the ninth and only saved by the bell in a punishing 10th that left him in serious trouble, bloodied and stumbling.

Tszyu dealt out more of the same in the 11th but the ultra-fit American, who has never been knocked out, kept his feet and took it the distance.

The victory improved Tszyu to 24-0-0, with 17 knockouts.