On 29 October, Singleton discovered a letter in his locker marked 'confidential'. He ripped it open to read that a sample taken on 13 October - the day after Denver's win over the New York Jets in London - returned an elevated level of the hormone hCG (human chorionic gonadotropin).

"I'm like, 'whoa, that's crazy'. I don't know how that would happen," he said. "I was walking into a meeting so just searched 'hCG hormone' and it pops up that you're either injecting it or you have testicular cancer.

"I'm kind of freaking out. I go home, I tell my wife and was like, 'well, I'm not taking anything', so maybe I should go to a doctor'."

Singleton's wife Sam, who gave birth to their first child Tallyn in February, booked an appointment for Monday, 3 November.

So when Singleton helped Denver beat Houston the previous day, he still did not know whether he had cancer or faced a drugs ban, and "it was kind of in my head the entire time, wondering what was going on".

After being diagnosed that Monday, Singleton said that "all I wanted to do was play Thursday night".

"My biggest fear was getting this game taken away from me, not on my own terms," he added. "I didn't want Houston to be my last game because of what was going to happen to me after [the Raiders game]. You don't know at that point.

"I came to the [team] facility, we talked it through and they were like, 'as long as you're in the head space to play, you can play. Let's do this'."

After testicular cancer surgery, heavy lifting or exercise is not normally recommended for about six weeks, but Singleton's was not as "invasive" as it might have been.

Further tests showed he would be able to make a swift return and, three days after undergoing surgery, he revealed all to team-mates and media on 10 November.

"I didn't know what everyone's reaction would be, but it's amazing how fast football doesn't matter anymore and everyone just cares about your health," said Singleton.

"You learn a lot of empathy, compassion from maybe [team-mates] you don't expect it from. That's been the best part through the whole thing. It's made it so much easier to have such a support group of best friends."

Singleton missed just one game - a crucial win over the Kansas City Chiefs - then Denver had a bye week before their leading tackler this season (95) returned on Sunday against Washington.

He broke up a big play in the final quarter before the Broncos won in overtime so after telling a sideline reporter he would try not to cry, Singleton "got a little emotional" after the game.

"So many guys and coaches on the other team said 'we've been thinking about you, we've been praying for you'," he said. "That showed how close this league is.

"It really meant a lot to me, that it's bigger than football. It meant something to everybody, so that was really special to me, and I kind of lost it at that point."

Testicular cancer is often treatable and is most common in men aged 15 to 49, according to the NHS., external

And although Singleton's tumour was discovered by accident, he urges men to think and talk about their health more often.

"I've already had people say 'hey man, I just went and got checked because of you'," he said. "I'm a perfect example of how, in 24 days, you can be completely 100% healthy again. It doesn't have to be the scariest thing in the world. It can be cured quickly.

"I've learned so much about being vulnerable, being able to talk about it. I've had the best conversations with so many people, learning about myself and what they're going through - it could be cancer, mental health struggles, physical [struggles].

"It's brought me really close to people so don't be afraid to be vulnerable because all it will do is build stronger relationships."

Last season Denver reached the play-offs for the first time since winning the team's third Super Bowl at the end of the 2015 season.

They have continued to improve in Sean Payton's third year as head coach, with Sunday's win their ninth in a row. The Broncos now have a 10-2 record, second only to the New England Patriots (11-2).

Denver's defence not only leads the league for team sacks (51), it is on course to pass the single-season record (72) and the Broncos have developed a knack for grinding out wins, with eight coming in one-score games.

"I think we knew from last year we were going to be special this year," said Singleton. "And I don't even think we've played our best game yet, not even close.

"We're doing things the right way to win games at the end. But there's stuff we can continue to get better.

"We can be like those 1997, 1998 teams, that 2015 team. At 10-2, you shouldn't be afraid to talk about wanting to go win a Super Bowl. That is our goal, and we're doing nothing but chasing goals over the next month."

With five games left, Denver look set to end the dominance of Kansas City (6-6) in the AFC West. After winning three of the past six Super Bowls, the Chiefs could miss out on the play-offs for the first time since the 2014 season and the division title for the first time since 2015.

That 2015 season ended with Denver winning the Super Bowl at Levi's Stadium, which also hosts this season's championship game, and Singleton believes that surviving a remarkable month could inspire him to a fairytale finish.

"I think my perspective will be different to everybody else for the rest of the season," he said. "I could have been done, so I'm going to cherish every week like it is truly my last ever playing.

"We want to win the Super Bowl in Santa Clara and we don't care what we have to do or who we have to go through to get there.

"I'm so excited every Sunday to see what we're going to do and hopefully we'll be hoisting that Lombardi [Trophy] in a few months."