By Sanjeev Shetty BBC Sport Online

It must be getting harder and harder for the casual boxing fan to know who really is 'the man'.

Consider that Lennox Lewis, reportedly on the verge of retirement, holds the World Boxing Council and International Boxing Federation heavyweight titles.

The WBO champion is Wladimir Klitschko, and many feel that the giant Ukrainian will rule the unlimited class for years to come.

Looking in from the outside is John Ruiz, the Boston-based Puerto Rican who holds the WBA title, but who has yet to forge a reputation.

Ruiz defends his title against Canadian Kirk Johnson on 27 July in Las Vegas at the Mandalay Bay Hotel.

The unbeaten Johnson enters the fight with as many question marks against his name as Ruiz.

His stamina and big fight temperament have been questioned, despite the fact that he has not suffered defeat.

There is no doubt that Johnson has exceptional speed and movement, but whether he will display the confidence to use them at this level is another matter.

The 28-year-old has recorded wins over fringe contenders such as Oleg Maskaev, Larry Donald and Dannell Nicholson, but in general his opposition has been mediocre.

Ruiz has two substantial names on his record - Evander Holyfield and David Tua.

Ruiz engaged in three fights with Holyfield and the series proved to be bizarre.

The first fight went to the 39-yeat-old living legend from Atlanta on what appeared to be a gift decision; Ruiz; Ruiz squared the series in the second fight, aided by some theatrics in the 10th round.

And last December, Holyfield appeared to, in the minds of everyone except the judges, win easily, with the fight scored a draw.

Ruiz and his team have put great emphasis on the achievement to fight Holyfield three times and come away with the belt.

But a prime Holyfield would have been fancied to despatch the likeable Ruiz in less than five rounds.

The Tua fight is one which will always haunt the champion - he was knocked out in less than a minute by the Kiwi in 1996.

It still seems that Ruiz is vulnerable to a big, solid heavyweight punch and he is fortunate to be facing Johnson, a man not noted for his power.

Whether Ruiz's style, which includes an annoyingly precise jab and sneaky right hand can keep the skilled Johnson at bay remains to be seen.

It may just be that the Canadian is one of those fighters who freezes on the big stage and allows Ruiz to dictate matters.

Alternatively, he could be one who rises to the challenge and slowly wears his foe down for a late stoppage.

In two other fights both taking place in America on Saturday, Clifford Etienne faces Francois Botha.

Botha has met and lost to three top heavyweights in the last three years - Lewis, Klitschko and Mike Tyson.

Etienne is a rising contender who always provides value for money with his aggressive style - he should have too much youth for the ageing Botha.

Youth is something that Larry Holmes lost in the 1980s, but he has forgotten more about boxing than his opponent this Saturday, Butterbean, has ever learnt.

This is essentially a last hurrah for Holmes, who has never forgotten the value of money - the fight will go out on pay-per-view throughout the United States.