Heavyweight world champion Andy Ruiz Jr has pledged to end Anthony Joshua's career after confirming for the first time that he will contest the rematch in Saudi Arabia.

The 29-year-old, who was born in America but fights for Mexico, shocked the division in New York in June when he inflicted a first defeat on Joshua to win the WBA, IBF, WBO and IBO world titles.

Ruiz is set to face the Briton again on December 7 in Diriyah - a fight announced by Joshua's camp earlier this month but not confirmed by Ruiz until now.

On Saturday the champion posted on social media: "I'm excited to announce my rematch with Anthony Joshua.

"In the first fight I made history and became the first ever Mexican/American heavyweight champion of the world.

"I am grateful to Saudi Arabia for inviting me. I took it to AJ in The Big Apple and I'm looking forward to ending his career in the Desert.

"Don't miss this fight!"