His favoured cross-country round started overnight and Nicholson is ready to step out of the shadow of a certain Sir Mark Todd.
For all Nicholson's success as a three-day eventer, the world No 1 has never tasted victory at Badminton - considered the pinnacle of the sport - nor won an individual medal at the Olympics. Four-time winner Sir Mark is royalty in an event where actual royalty compete (the Queen's granddaughter Zara Phillips is among the field) and has a pavilion named after him, just a stone's throw from the arena action.
But this time it is Nicholson, the "almost" man, who is front and centre. He's on the cusp of a rare "Grand Slam" of blue chip events after his two recent wins at Burghley and Kentucky, going head-to-head with his fierce rival Fox-Pitt, the local British favourite.
There's a genuine buzz in the air at Badminton; with supporters taking sides with "Team Andrew" or "Team William" T-shirts.
Throw Jung into the mix for his first crack at Badminton - the German is the present Olympic, world and European champion and the only person to hold all three titles - and the equestrian world is practically salivating.
"This arguably is the best field we've ever had," says tournament director and course designer Hugh Thomas. "Nicholson versus Fox-Pitt versus Jung is probably the most exciting finish in our sport. And there's probably a dozen other riders who could win."
There's US$350,000 ($410,000) of Grand Slam prizemoney at stake, as well as the chance for Nicholson to scratch an itch that doesn't seem to go away. He's completed the difficult course 32 times, a record, but only placed on the podium once - runner-up to Fox-Pitt in 2004.
"I was in the lead after the dressage and then we had torrential rain ... I was last to go in the cross-country, so the ground was deep and, being at the end, you get the worst of it," Nicholson told the Herald on Sunday after the first dressage round.
"So I ended up getting more time penalties than the winner. That's not bad luck, that's weather, that's part of an outdoor sport. You take it as it is."
He freely admits that winning Badminton would mean everything to him: "Winning here would be the pinnacle of my career, really. It's like Wimbledon for tennis. All the best riders want to be at Badminton.
"There's something about this place. The crowds which come to the cross-country are incredible ... there's a real buzz ... it's the home of our sport.
"I've won plenty of other events but never here. So hopefully this is the year we're going to change it all."
Striding through the grounds to get to his next appointment, Nicholson good-naturedly greets well-wishers and shrugs off questions about the hoopla of the potential Grand Slam. After winning Burghley in 2012, he admits to targeting the win at Kentucky last week to put himself in a position for the rare sweep. Only Pippa Funnell has achieved it before.
Now he's concentrating on the task at hand: "Win Badminton and we win the Grand Slam; it's as simple as that. I've never been able to come here with the calibre of the horses that I have.
"So I'm feeling positive. It's only dressage; you don't need to be in the lead but you need to have a good score. As long as we can keep tabs on the leaders after the dressage, we're in with a shot."
With a firm handshake, he looks at the cloudy skies and says goodbye with a wry grin. "Looks like we might get a bit of rain."
