Frank Warren just announced the following news to fight fans: "Due to an injury suffered by Billy Joe Saunders, unfortunately he has had to withdraw from his June 23rd fight with Martin Murray at the O2 Arena. A full statement on the show will be made tomorrow [June 4]. We apologise for any inconvenience."
Saunders (26-0-KO12) had been due to make the fourth defence of his title at The O2 but suffered a setback in training camp.
The champion said via his social media account: “Apologies for any inconvenience but due to the injury I had to withdraw from the fight on June 23.
Martin Murray next fight revealed
All the results from the Billy Joe Saunders vs Shefat Isufi Stevenage card
Billy Joe Saunders vs Shefat Isufi weights and running order
Fans have initially reacted with their disappointment on Twitter and are unsure if the event will proceed with no other worthy headline acts appearing on the card.
It's frustrating news for the challenger, Martin Murray, having already suffered a postponement from April 14 - the original fight date - when Saunders withdrew with an injury once before.
Saunders, 28, was forced to pull out of the first meeting between the two men when he damaged his hand during training. But now the 26-0 southpaw has reportedly withdrawn from the rematch once again, this time due to a hamstring injury.
The news comes after claims that talks between rival middleweights Canelo Alvarez and Gennady Golovkin have broken down over their proposed super-fight in September; Golovkin is believed to be demanding improved terms from the split that he received during their controversial draw last September after Canelo's recent failed drugs test.
The Mexican's subsequent six-month suspension ruled him out of a May 5 fight with Golovkin that had been in the calendar for some time, leaving the WBA, WBC and IBF titlist without an opponent at short notice.