Jerry Rice, one of the greatest players in American football history, is sitting in a room beneath Wembley Stadium.
Outside, final preparations are being made for tomorrow's annual NFL fixture in London, in which Rice's former team, the San Francisco 49ers, take on the Denver Broncos.
It is more than five years since Rice played a sport in which he still holds almost every record for wide receivers, but a glint appears in his eye as he considers what it would be like to enjoy one last hurrah.
"If I could put that uniform on one more time and run out on that field I would," he says. "This would have been the ultimate. I played in London in pre-season matches, but these guys have the chance to play here, in the regular season, with 85,000 people going crazy.
"You can tell that American football is something special here. There will be a lot of people in the stand getting excited. The energy here is unbelievable. The crowd's energy was something I always fed off."
At 48 Rice is still supremely fit, even if nearly a stone heavier than in his playing days. "I'm a little bit more muscular now," he says, before adding with a smile: "My girlfriend wanted me to put on a bit more."
As a player Rice would weigh himself every morning. If the scales topped 189lb his colleagues would arrive at training to find him already on the treadmill. His appetite for work was legendary. "I was determined to be the best football player I could possibly be, so I was willing to go to extremes, even in the off season," he recalls. "When we went to training camps I was already in shape, whereas a lot of guys used them to get into shape."
Rice, who is here as a television pundit, reckons his conditioning was the key to his longevity. In a physically demanding sport where careers average just four years, Rice played for 20 seasons, the first 16 with San Francisco, with whom he won three Super Bowls, followed by spells at Oakland, Seattle and Denver.
Tearing knee ligaments in 1997 ended a run of 189 consecutive appearances. Remarkably, he was back playing 14 weeks later. "I was in a cast, which they wanted me in for four to six weeks, but it was driving me crazy," he recalls. "I remember going downstairs to the garage and picking up a saw and cutting it off. After that they put me in a more flexible support. It was a difficult time. I didn't feel like I was part of the team. I couldn't sweat with them or go to battle with them."
While Rice does not think the NFL is more physical today, he reckons players are bigger and faster. He has been concerned by this season's spate of head and neck injuries. "If you lead with the crown of the helmet I believe your intention is to hurt," he says. "And if you don't hurt the player you're trying to hit then you can hurt yourself."
Nevertheless, he does not think all contact with the head should be outlawed. "Those were the hits that they used to show for commercials," he says of some of the more shuddering collisions. "Football still has to be a physical sport."
Rice maintains a strict training regime. "It jump-starts my day," he says. "Monday, Wednesday, Friday I might go for a distance run of five to 10 miles. I go to the gym on Tuesday and Thursday. I'm always looking to challenge myself."
He never does anything by half. Rice appeared on Dancing with the Stars – the American version of Strictly – and impressed with his work ethic, finishing runner-up with his partner, Anna Trebunskaya. "I was like a fish out of water," he admits. "It was so difficult. Ten weeks and you're working every day. It was an experience of a lifetime and I enjoyed it, but I did not know the magnitude of it until I got into it. It's hard. You do a routine, add another and then someone criticises you after you've worked so hard."
Rice threw himself just as wholeheartedly into golf, which was an obsession in his playing days. "It's one of those games where you can't blame anyone else – you get out of it what you put into it," he says. "I would get up at four in the morning and go and hit golf balls. Then I would go to work from, say, eight till four, then I would go back and hit more golf balls."
He made his professional golf debut in some minor events this year. "My golf is OK, but I don't totally commit to it," he says. "I probably play twice a week, but then I have some weeks when I don't have time to play at all. As a professional golfer you have to be hands-on, have a coach and work at it every day. I like doing a variety of things, but playing golf every day, making the cut and having some success would be the ultimate dream."
Rice's caddie told him to slow down. "Before I select a club or if I'm reading a putt, I need to make sure exactly what I want to do," he says. "What I noticed from playing in those tournaments was that these guys are so precise about everything. They don't pull a club until they're ready to commit to that shot. Sometimes as a football player you have to be a bit more creative. You go on a run and you have to adjust."
As for broadcasting, Rice again does not feel ready to make the commitment he feels would be necessary for a major career. "I want a little bit of freedom after sacrificing so many years to football," he says. Coaching, except perhaps at school level, does not appeal either. "Coaches don't really have a life. They're working all the time."
Instead Rice spends time with his children (Jaqui, 23, Jerry Jnr, 19, who plays gridiron at university, and Jada, 14), gives motivational speeches and does promotional work. He also enjoys watching the 49ers, although they have lost six of seven this season. "They're a very young group," he says. "You have to have leaders and I just don't see anyone taking on that leadership role right now."
You sense Rice would love nothing more than to provide that leadership. "Every day I miss playing – going out there and entertaining so many people on that big stage," he says. "When you play in the Super Bowl, the high that you're on playing in a game of that magnitude is hard to replace."
The San Francisco 49ers take on the Denver Broncos at Wembley tomorrow (kick-off 5pm, live on Sky Sports 2 and BBC Radio 5Live, with highlights on BBC1 at 11.35pm)