Transcript for A week from now marks 20 years since Princess Diana's death
Finally, princes William and Harry in a new interview, revealing they felt their mother was right there with them. Reporter: It is the last image the world saw of Diana. Then learning of the crash. It is here on Saturday that the funeral for Diana, the princess of Wales will be held -- Reporter: It's hard to believe, the world will mark 20 years since her death. Prince Harry on the Paparazzi, who followed his mother into that tunnel. One of the hardest things to come to terms with is the fact that the people that chased her through -- into the tunnel were the same people that were taking photographs of her while she was still dying in the backseat of the car. She had had quite a severe head injury, but she was very much still alive in the backseat. Reporter: Two boys walking alongside their mother's casket. Now revealing he felt his mother was there. It was one of the hardest things I had ever done. I felt like she was walking beside us to get us through it. Reporter: He said he understands why his mother did that interview whenhe talked about her troubled marriage. There were three of us in this marriage, so it was a bit crowded. Reporter: Prince William saying, I can understand having sometimes been in those situations. You feel desperate, and you feel terrible that things are being said that are untrue. The easiest thing to do is say or go to the media himself. It either makes or breaks you, and I wouldn't let it break me. I wanted it to make me, and I wanted her to be proud of the person I would become. I didn't want her worried or her legacy to be, you know, William and/or Harry were completely and utterly devastated and all their hard work she put in would go to waste. I'm David Muir. I hope to see you right back here tomorrow.
This transcript has been automatically generated and may not be 100% accurate.