Roy Jones Jnr will attempt to make history after signing to fight WBA heavyweight champion John Ruiz on 1 March 2003 in Las Vegas.

The 33-year-old Jones Jnr will move up from light heavyweight - where he holds three titles - to face Ruiz, who won the WBA title from Evander Holyfield in March 2001.

"The contracts are signed. Roy has signed, Ruiz has signed, Don King has signed and I have signed. I feel elated," promoter Murad Muhammad told boxing website Secondsout.com.

Under the terms of the agreement Jones Jnr will receive a $10m guarantee and 60% of the profit made from pay-per-view sales while Ruiz will receive 40% of the return.

Jones Jnr, considered by many to be the finest boxer of his generation, has received criticism for the quality of opponents he has faced in recent years.

In taking on Ruiz, a man who naturally outweighs him by 40lbs, he will be taking on the biggest challenge of his 14-year career.

With middleweight, super-middleweight and light heavyweight titles on his resume, Jones Jnr has beaten every man he has faced.

The only blemish on his record of 47 wins and one defeat, a disqualification loss to Montell Griffin, was swiftly avenged.

Ruiz, whose record stands at 38 wins, four defeats and one draw, is reckoned to be one of the poorest heavyweight champions ever.

He made his name through a trilogy of fights with Holyfield, with each man winning one, with the final bout declared a draw.

The only man to have won world titles at middleweight, light heavyweight and heavyweight was Britain's Bob Fitzsimmons, who achieved the feat between 1891 and 1905.