He famously beat Hasim Rahman in 1998 but was subsequently outpointed by Lennox Lewis in 2000.
But Tua had an extremely long career fighting until 2013 when he eventually retired on the back of a second consecutive loss.
Ruiz had some incredible memories in the sport during his stint.
He was first controversially outpointed in a huge fight with Holyfield in 2001.
But he famously captured a world title with a win over ‘The Real Deal’ on points nine months later.
It was an incredible achievement which saw him hold the title for just one win.
He was beaten by truly gifted fighter Jones Jr, who too beat him on points in 2003.
Ruiz after 2004 when he lost the belt for a second time failed to beat any of the leading names.
He suffered two defeats against 7ft 2ins Russian giant Valuev.
Then his final bow in the sport came against powerful British fighter Haye, when he was far from his best.