Sexton has beaten Martin Rogen in two Commonwealth bouts this year
Sam Sexton has pulled out of his bid for the British heavyweight title against Danny Williams.
The 25-year-old from Norwich is currently attending his mother's bedside at Addenbrooke's Hospital after she suffered a brain aneurysm.
His management team released a statement on Sunday.
"Sam has been unable to continue his training for the past week and for the foreseeable future until his mother is out of danger," it read.
"After extensive discussion with his trainer it was decided that Sam was not in a fit state of mind for any fight, let alone a championship fight."
Derek Chisora will step in to face Williams at Upton Park on the undercard of Kevin Mitchell's Interim WBO World lightweight title fight with Michael Katsidis.
The 25-year-old said he had sympathy for Sexton who he beat in June 2008, the Commonwealth champion's only professional defeat.
"First of all my thoughts are with Sam and his family at this time and I hope his mother makes a full recovery.
"The opportunity to fight Williams again was presented to me and I took the fight straight away," he said.