The Archbishop of Canterbury urged people to pray for Meghan Markle's father after it was confirmed the Prince of Wales would step in for him at the royal wedding.
The Most Rev Justin Welby, who has been at a number of rehearsals ahead of today's eagerly anticipated ceremony, said it is "wonderful" that Charles will walk Ms Markle down the aisle.
Ms Markle's father, Thomas Markle, was forced to pull out of performing the fatherly duty after undergoing heart surgery in a dramatic upset just two days before the wedding.
Asked yesterday about whether Mr Markle will be included or mentioned in prayers on the wedding day, Mr Welby said: "I really couldn't comment on that side of things, except obviously, as with all times like this where someone's ill, you remember them in your prayers.
"And I hope people will pray for him, and pray for the couple and pray for everyone involved on the process tomorrow."
Talking about the Prince of Wales being chosen to walk Ms Markle down the aisle, Mr Welby said Charles is "someone of great care and affection".
He added: "He's a very warm person and that he's doing this is a sign of his love and concern and support. And I think it's wonderful. It's beautiful."
Mr Welby said of Harry and Ms Markle: "They're very, very sensible, they're a very self-possessed couple.
"And at the rehearsal they just got on with it and it was very relaxed, laughing and enjoyable."
Prince Harry's nephew and niece, Prince George and Princess Charlotte, are among the six bridesmaids and four pageboys.
Asked if someone is in charge of making sure all the children behave themselves, Mr Welby responded: "I'm glad to say that's really not our problem.
"I'm sure there will be. It will be beautiful."
Mr Welby did an interview alongside The Most Rev Bishop Michael Curry, the 27th presiding bishop and primate of the Episcopal Church, who will give an address at the wedding.
The preacher, from Chicago, will attend the service at St George's Chapel, Windsor, at which Mr Welby will officiate.
The Episcopal Church is an offshoot of the Church of England in the US and forms part of the broader Anglican Communion worldwide.
Ms Markle was baptised by Mr Welby ahead of her wedding to the prince, whose grandmother, the Queen, is head of the Anglican Church.
Mr Curry said the marriage is significant in the sense that "different worlds are being brought together" but he added that we are "part of God's family", saying: "In a sense it's different and in a sense, no, it's being who we are."
Mr Curry continued: "My prayer really is that the sermon will be a word of hope, be a word about Jesus Christ and the love of God that he has shown us how to live in our lives, and change the world by doing that. That's my prayer."
The preacher said he felt "genuinely excited and hopeful and prayerful" about today's ceremony.