New Olympic champion Tom Daley revealed he could not walk just weeks before winning diving gold with Matty Lee at Tokyo 2020.
The 27-year-old had knee surgery in June but recovered to take a faultless victory in the synchronised 10 metres platform on Monday.
The pair beat China by just 1.23 points after a nerveless display as Daley collected his third Olympic medal.
But Daley admitted he was struggling to even make it to Japan after an operation last month.
He said: "I had a pretty bad knee injury. Basically, I haven't said this yet, but in June I tore my meniscus and underwent knee surgery.
"There was a chance that I wasn't actually going to be able to be here in the first place. I tore my meniscus and had to get it removed at the beginning of June.
"It was something that apparently had been there for a while. It's the cartilage in my knee and it flipped up and got stuck in my joint.
"I couldn't actually straighten my leg. It was locked in this position (angled), so I couldn't actually walk or do anything. They explained the risks with surgery – but it's either I can't walk or surgery so I had to risk it.
"There was a lot of visualisation, a lot of trust in my experience and the process of getting back.
"They said it would be four-to-six weeks and it was six weeks by the time we left. I am just extremely happy and thankful for all the physios and doctors, strength coach, my coach for making it possible that we could even dive today."
Daley made his Olympic debut as a 14-year-old in Beijing and won bronze at London 2012 and Rio five years ago.
Daley and Lee were not expected to win, with China the favourites, but they never dropped out of the top two and finished with a score of 471.81 following an exceptional forward four-and-a-half somersaults pike when the pressure was on in the final round.
China's poor fourth-round dive let the Team GB pair take the lead and they never looked back, with the ROC claiming bronze.
"It's kind of unbelievable. I dreamt, as has Matty, since I started diving 20 years ago for this moment," said Daley.
"I thought I was going to win an Olympic gold in Rio and that turned out the complete opposite by a long shot.
"My husband said to me my story wasn't finished and my son (Robbie) needed to be there to watch me win an Olympic gold medal.
"I can say my son watched me become an Olympic champion, albeit on TV as they couldn't be here. It's such a great feeling."
Lee added: "It felt crazy, obviously. In October 2018 I moved my whole life to London from Leeds. I was away from my family and friends, everyone. I had nothing in London. Our aim was to win an Olympic medal.
"To be able to put the well-deserved gold medal around his neck was really special to me and I'm very very proud of him. Obviously it's my dream to be a gold medallist, an Olympic gold medallist, and it's great to be able to have won that with him."
Daley's husband Dustin Lance Black won the Best Original Screenplay Oscar for Milk in 2008 but Daley admits he does not know whether his medal or the Oscar will take pride of place at home.
He said: "My husband's Oscar goes in the downstairs loo. People often mistake it for a loobrush. We had to get an Oscar loobrush because people were picking it up and realising it was an actual Oscar, not just a toy.
"I don't know why he does that, he says he doesn't want to give it any more power than it needs. He's done it and moving on to the next thing."
