But after enjoying the buzz of mixing with those already displaying medals around their necks, on Thursday morning in Tokyo it was time for the two Englishmen to see what they could bring to the table.
For Casey, day one at Kasumigaseki Country Club went well; he fired a 4-under 67 to end the day in a tie for fifth - four back from surprise leader Sepp Straka of Austria.
A break for lightning disrupted play at one point but Fleetwood had the chance to match his GB teammate after moving to 3-under with back-nine birdies at 11, 13, 15.
However, Fleetwood's first day as an Olympian acted as a reminder that highs and lows are all part of the experience.
Instead of the closing birdie that would have taken him to tied fifth, he ended with a double bogey six to slip back to 1-under and tied 31st.
It's early days but the gap will be a concern. When Justin Rose won Olympic gold in Rio, he was never outside the top four at the end of each round.
Here's how the race for golf stands after 18 holes:
Gold medal position
-8 Sepp Straka (Austria)
World No.161 Straka leads the race for gold after a bogey-free 63. The Austrian went out in 4-under 32 after picking up shots at 3, 5, 6 and 8. He produced another surge on the back nine with gains at 13, 14, 15 and 17 to secure the lead.
His position is a surprise; Straka has missed six of his last seven cuts on the PGA Tour although he did manage T10 at the Travelers Championship during that run.
Silver medal position
-7 Jazz Janewattanond (Thailand)
Jazz is ranked 150th in the world and, like Straka, didn't have much form coming in. The Thai had missed four of his last six cuts although he did make the weekend at the Open Championship when T46. The 25-year-old has six Asian Tour wins and also a Japanese Tour victory so he's a force on his home Asian turf. Like Straka, he kept a clear card, making birdies at 1, 8, 9, 10, 11, 13 and 18.
Bronze medal position
-6 Thomas Pieters (Belgium)
-6 Carlos Ortiz (Mexico)
Pieters likes the big occasion. He's had a top four in the Masters, a sixth in the PGA and a pair of top fives in WGC events. In addition, he just missed out on a medal in Rio five years ago when finishing in solo fourth. The Belgian's form has been bubbling under, with T12 in the Irish Open and T35 in the Scottish Open his last two starts. Pieters was just 1-under on the front but made eagle-2 at 11 before adding birdies at 13, 17 and 18.
Ortiz adds to the international leaderboard and the Mexican's 65 came courtesy of seven birdies (3, 6, 8, 10, 13, 14 and 15) against a lone bogey (9). Like the top two, his form has been fairly poor with just one top 20 (T16 Memorial) in his last 12 starts.
-5 Joachim B Hansen (Denmark), Jhonattan Vegas (Venezuela), Juvic Pagunsan (Philippines)
-4 Sebastian Munoz (Colombia), Paul Casey (Great Britain), Anirban Lahiri (India), Alex Noren (Sweden)
-1 Tommy Fleetwood (Great Britain), Shane Lowry (Ireland)
Evs Justin Thomas (United States)
Paul Casey quotes
"I am just really proud to be honest - that is the coolest thing - because I've thought about it for so long.
"It is a solid start. I don't know what the winning score is going to be - we've predicted 15, 16 (under par), something like that.
"We will have to see how it pans out. You've got to just eliminate mistakes, and what I didn't want to do was shoot myself in the foot.
"They don't put pressure on you, Team GB, it is never about that. It has not been mentioned once that we need to deliver.
"But you feel that with the other athletes because everyone else is performing so brilliantly, and I want to perform and live up to their expectations as well."
Sepp Straka quotes
"When they had them (the Olympics) in Brazil I was watching, I wasn't close to qualifying back then but I was watching and it seemed like a cool event.
"Everybody that I knew that went over there and played just raved about it. So, I knew at that point that this was going to be on my radar and definitely wanted to play well so I could play my way in."
Thomas Pieters quotes
"I played the back nine blind, my caddie just said, hit it there. I was hitting my driver pretty well and gave myself plenty of chances.
"This morning, when you get to the course and you realise this is like once every four years (or five this time), it hits you. So yeah, I was really looking forward to teeing off.
"Being from a small country - we have got two medals up to now - you just want to get one more for your country. I mean (winning a medal) is like legendary status back home. I just want to get a medal, it would be lovely, but there is a long way to go."