On Wednesday, he was laughing and joking with his former Scotland amateur team-mate, Bob MacIntyre, as they played a practice round together at Carnoustie.
Twenty-four hours later, the 25-year-old Glaswegian sits one shot off the lead after the opening round of the 20th Alfred Dunhill Links Championship, having opened with a seven-under 65 at St Andrews.
The sparkling start came alongside Brad Simpson, the lead singer with British rock band the Vamps, the pair hitting it off to such an extent that they share top spot in the team event following a 12-under 60.
“I played well,” reported Ferguson of a bogey-free individual effort, which left him sitting joint-fifth as the pace was set in the $5.5 million event by two-time winner Tyrrell Hatton, Belgian Nicolas Colsaerts, China’s Haotong Li and Spaniard Adri Arnaus.
“I woke up about three hours before I should have because of the rain battering off my caravan – and I thought: ‘Oh no!’ After the first couple of holes, it brightened up and I got off to a nice start, then rode the momentum.”
A former Scottish and British Boys’ champion, Ferguson currently sits fourth in the Challenge Tour’s Road to Mallorca Rankings and is on course to secure his European Tour card for the first time next season.
“I was going to take this week off from the Challenge Tour and, when I got the invite, it was just amazing to be coming here and playing,” he said of getting a taste of main-tour action. “It’s a free week for me, so I’m just enjoying it, seeing what I can do. It would be unbelievable to win here, a dream come true, but there’s a long way to go.”
Ferguson caught Covid as he was preparing for an event in the Netherlands at the end of last month and found himself locked in a hotel room for 10 days.
"The first four days I didn't want to get out of bed,” he said. “One minute I was sweating, the next I was freezing. It was crazy. My dad had it at the same time and he ended up moving into my flat to isolate and we were messaging each other saying this is boring.
"I've never even had an injury before. Then, for two weeks I didn't get any points and people were catching me up. Then my back was killing me which I don't suppose was surprising after sitting on my arse for all that time watching Netflix.”
Ferguson played on the same 2015 Walker Cup team as Grant Forrest, who recorded his breakthrough European Tour win in the Hero Open at Fairmont St Andrews in August, and is also good friends with MacIntyre, Calum Hill and Connor Syme.
"What I am enjoying is turning up this week and seeing Calum and playing with Bob and Connor and Grant,” he said. “The first thing they said to me was I'm playing great this year and it's really good and they've been checking my results.
“It's so nice having that. They could have been snide and made out they hadn’t noticed. But nothing has changed. They are a great bunch and it's where I also want to be.”
For the next couple of days, though, he is perfectly happy to be alongside Simpson, who is making his second appearance in the event and was being ribbed by another singing artist, Ronan Keating, as he finished his round.
“I'm a big Vamps fan and know a lot of their songs,” said Ferguson, who is managed by Niall Horan, of his playing partner. “He's such a nice guy and once he settled he played some great stuff. I asked him to give me a wee shout out to his followers.”
For the record, Simpson has 1.7 million of those on Twitter alone and he, too, enjoyed his day.
“Ewen played fantastic, so I was kind of following his lead today,” said Simpson. “There was a connection between us from the start. We had a nice, fun round today.”
Hatton, the champion in 2016 and 2017, made his promising start by coming home in incredible 29 shots at Carnoustie, where he eagled the 14th in the middle of birdies at the 10th, 11th, 14th, 15th and 17th.
"I didn't actually realise,” admitted the Englishman of his scoring feat. “It’s always nice to start pretty good around this golf course. You go to the other ones and feel like you've got slightly more of a chance than here so we'll see what the week brings.”
Hatton, who played in last week’s Ryder Cup defeat at Whistling Straits, is being partnered by his dad Jeff, who is also his coach. “He hasn't looked at my swing or anything,” he reported. “I think he's a bit too excited to play these courses for the first time.
“I imagine he's probably quite tired. He normally plays like once every six weeks and he did 18 holes on Tuesday and he did nine holes yesterday and obviously another 18 today.”
Both starting out at Kingsbarns, Richie Ramsay and David Law were next best among the Scots with 67 and 68 respectively, with MacIntyre opening with a three-under 69 at Carnoustie.
“I played great,” said MacIntyre, who dropped his only shot of the day at the par-3 16th. “The first five holes I was just trying to make pars because of the weather. I made an unbelievable par save at one, and I hit a driver up two that went just 220 yards, and that was right out of the middle.
“I was just praying that the weather was going to ease up, and it did. Scoring is there, you're seeing scores now, but three-under at Carnoustie on any day is pretty good.”