(THE GUARDIAN) - Anthony Joshua will fight Joseph Parker for the World Boxing Association (WBA), International Boxing Federation (IBF) and World Boxing Organisation (WBO) heavyweight titles at Cardiff's Principality Stadium on March 31.

The Briton holds the IBF and WBA titles while Parker is the WBO champion.

Joshua's promoters Matchroom Boxing confirmed the deal on Sunday (Jan 14), concluding weeks of fractious negotiations between the two sides.

Joshua said: "It is a unification heavyweight championship fight. We all know what happened last time I was in a unification heavyweight championship fight - it was gruelling, it was interesting and we both left the ring with masses of respect.

"These fights aren't easy because there is a lot on the line, so respect to team Parker for taking the challenge. I am looking forward to it, training camp is under way and before you know it, March 31 will be upon us."

Joshua unified the WBA and IBF titles with his win over Wladimir Klitschko last April , before subsequently battling out a late stoppage win over Carlos Takam in Cardiff in October.

The 26-year-old Parker had made his UK debut one month previously, when he earned an underwhelming majority points verdict over challenger Hughie Fury at the Manchester Arena.

Parker said: "Anthony Joshua is in for a huge shock. A couple of months ago, I heard him say, 'Why should I be worried about this little kid from New Zealand'?

"Well, now he's about to find out. And the world is about to find out whether AJ can really take a punch. My entire existence is now devoted to proving what the boxing world already knows."