Prince Philip has been admitted to a London hospital for hip surgery, reps for Buckingham Palace confirmed Tuesday.
The Duke of Edinburgh, who is 96 years old, will undergo the planned operation Wednesday at King Edward VII Hospital.
On Sunday, Queen Elizabeth II's husband was notably absent from his wife's side as she attended Easter services at St. George's Chapel. Also missing Sunday morning were Meghan Markle and Prince Harry, who will wed at the same chapel next month.
See Queen Elizabeth and Prince Philip through the years:
Concerns about Prince Philip's health have escalated since he retired from his royal duties in August 2017, after more than 60 years of service.
He was in good spirits upon announcing his retirement: When a palace guest said he was sorry to hear that the Duke would soon "stand down," he jokingly responded, "I can't stand up much longer."
Queen Elizabeth and the Duke of Edinburgh married in 1947, five years before she would gain her current royal title.
See photos from Queen Elizabeth and Prince Philip's wedding: