The Australian, who lost 6-3 3-6 7-6 (8-6) 7-6 (7-4), is a big basketball fan and said: "I never met Kobe, but basketball is practically my life. I watch it every day. I've been following it for as long as I can remember.
"When I woke up to the news, it was pretty emotional. It was pretty heavy all day. It's just tough. It's horrible news.
"If you look at the things he stood for, what he wanted to be remembered by, I felt like, if anything, it helped me tonight. When I was down a break in the fourth, I was definitely thinking about it. I fought back."
Nadal had an association with Bryant through Spanish basketball star Pau Gasol, Bryant's former Lakers team-mate.
The world No 1 said: "He (Gasol) always told me he is a spirit of hard work, he always wanted to increase his level. He is a true inspiration for the world of sport and for a lot of kids.
"This is one of those days you want to forget but of course Kobe Bryant will be in our hearts and in our minds for the rest of our lives."
Bryant took up the sport following his retirement from basketball and was friends with a number of leading players.
He was at the US Open last summer and sat in Naomi Osaka's box for one of her matches. He also wrote a children's book about tennis released last year called 'Legacy and the Queen'.
Novak Djokovic, who will play his quarter-final in Melbourne on Tuesday, was among those who knew the 41-year-old.
Writing on Instagram on Monday after learning of the death of Bryant and his daughter Gianna, the world number two said: "My heart truly mourns over the news today.
"Kobe was a great mentor and friend. There are not enough words to express my deepest sympathies to the Bryants and every family suffering from this tragedy.
"May God bless you and your Gianna. Thank you for being there for me and inspiring the entire world. Thank you for showing all of us athletes how to compete and respect sport.
"Thank you for the greatest legacy you leave behind with us. I'll never forget your smile spreading positive energy everywhere you went. You and your daughter will live forever in our hearts."
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Djokovic had spoken about his friendship with Bryant in an interview on ESPN only a few days ago, describing how the LA Lakers star had helped him when he was going through a difficult patch in his life and career.
Djokovic said: "He was one of the people that was really there for me and could give me some very valuable advice and guidelines to believe and trust in myself.
"I'm very grateful to him for being there for me, for being very supportive. I love Kobe - who doesn't? He's an amazing guy and one of the best basketball players and athletes of all time."
Maria Sharapova was another player who said Bryant had helped her through tough times.
She wrote on Twitter: "Kobe and Gigi. This is incredibly difficult to process. I will never forget your generosity, and the time you set aside in some of my most difficult moments. I am forever grateful. My heart is with you and your beautiful family."
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In a post on Instagram stories, Andy Murray wrote: "This has hit me hard. Thinking of all his family, friends and colleagues."
Players past and present also paid tribute to Bryant, including Coco Gauff, Jimmy Connors, Jo-Wilfried Tsonga, Karen Khachanov, Simona Halep, Naomi Osaka, Kirsten Flipkens and Anastasia Pavlychenkova.
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