Prince Philip reportedly battled through a cracked rib during last weekend's Royal Wedding after slipping in the bath days beforehand.
The 96-year-old royal is said to have suffered the injury days before the ceremony after falling in the bath - six weeks after he underwent hip replacement surgery.
A royal insider told The Sun newspaper: "The Duke is not a fan of showering and prefers to bathe.
"But he's a determined man and nothing was going to stop him attending nor would he take any kind of walking aid."
Last week, Buckingham Palace confirmed Philip - who retired from royal engagements last year - would attend the nuptials following speculation he may not be present after undergoing hip replacement surgery in April.
That came after the Duke of Edinburgh did away with his crutches just days before the Duke and Duchess of Sussex - who was previously known as Meghan Markle - tied the knot at St George's Chapel, Windsor Castle.
A source said at the time: "The duke is already walking unaided. He has amazing willpower. When he sets his mind to something he gets on and does it.
"He has been walking up and down stairs several times in succession.
"He has also been charging across rooms at full speed. He even had to be told to slow down."
Philip went under the knife on April 4 at King Edward VII Hospital in central London to replace the joint, and he subsequently spent nine days on bed rest before being allowed to return home.
When he left the medical facility, a spokesperson for Buckingham Palace said in a statement: "His Royal Highness The Duke of Edinburgh left King Edward VII's Hospital at midday today following a hip replacement operation last week.
"The Duke will continue his recovery at Windsor. His Royal Highness would like to convey his appreciation for the messages of good wishes he has received."