Before the Games much was made of Great Britain's women's swim team - who were expected to medal at the expense of their male colleagues.
But forget girl power, down at the Olympic pool it was a Boyzone and Jamieson was taking the lead, qualifying quickest into Wednesday's 200m breaststroke final with another storming swim.
And he took nearly two tenths of a second off the national record he set just a few hours earlier when he clocked 2:08.20, the third fastest time in the world this year.
Now he enters the final with a real chance of becoming Britain's first breaststroke gold medallist since Adrian Moorhouse's success in Seoul 24 years ago and it's all the more remarkable considering few considered him a serious medal prospect.
In addition best friend and training partner Andrew Willis is also right in medal contention, after progressing as the third fastest qualifier.
However, 23-year old Jamieson, who celebrates his birthday on Sunday, was keen to play down expectation of the gold medal the nation is craving.
"I’m pretty happy with how I've done so far," he said, with no hint of an understatement.
"I knew I was going to have to improve on the heat and I’m swimming full of confidence at the moment, especially racing in front of this crowd. They are making such a difference and it makes it a lot easier to swim fast.
“They were bringing me home in the last 50 metres, and I hope they can make even more noise in the final and myself and Andrew can shave some more time off.”
Chief among Jamieson’s threats will be Japan’s four-time Olympic champion Kosuke Kitajima and Hungary’s two-time world champion Daniel Gyurta plus American Scott Weltz and another Japanese swimmer Ryo Tateishi, who is second fastest in the world this year.
“I’m not getting ahead of myself, there is a long way to go,” said Jamieson.
“There are some massive names in this field – guys much more accomplished than me at this level.
“I’m swimming well and full of confidence. I’d just like to post another best time in the final and hopefully that’ll put me where I want.”
Jamieson has certainly benefitted from his domestic rivalry with Willis, while another training partner and fellow Scot Kris Gilchrist, played a great role in pushing them both in what was the most competitive event at the Olympic trials earlier this year.
But Jamieson has still been able to fly under the radar, with all the focus on Adlington, Keri Anne Payne plus other medal contenders Fran Halsall, Ellen Gandy and Lizzie Simmonds.
“Over the last few years I think the British girls have been stronger, but the guys are desperate to step up,” he added.
“We’ve had some really good swims so far this week, and I’m sure there’s some more to come.
“Training together, it’s obviously a pretty competitive atmosphere, and that’s shown in both our performances this week. Hopefully we can both keep that going in the final.
“I’ve just got to rest up and try to do the same again.”