Despite their opponents for the day, Pep Guardiola's free-scoring champions Manchester City, Hasenhuttl had named Kayne Ramsay in his defence.
It marked a landmark moment for the teenager by making his debut, but also for the Premier League.
At the age of 18 years and 81 days, Ramsay became the youngest player in the top tier to start a match this campaign, surpassing Fulham's Ryan Sessegnon and Tottenham's Oliver Skipp.
On the Thursday evening before the game, team-mate Pierre-Emile Hojbjerg had waited behind at training to see if young Ramsay needed a lift home. Three days later, he was playing alongside him in defence.
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Ramsay's rise can be seen as that debut came just three months after signing his first professional contract.
It was a baptism of fire for the youngster but his relegation-threatened team managed a respectable 3-1 defeat to City.
Boss Hasenhuttl had spoke about giving "jewels in the academy" a chance and he was impressed with the youngster.
The new coach said: "It was a very important game for Kayne and I think he did a good job.
"I think he will learn a lot as it was one of the best teams in the world we came up against. It's an amazing experience for such a young guy like he is."
Ramsay joined a star-studded list of alumni at Saints, following in the footsteps of Gareth Bale, Alex Oxlade-Chamberlain, Luke Shaw and Adam Lallana to emerge from the academy.
Yet the youngster's formative years were spent 65 miles up the M3 at Chelsea's Cobham training base.
Ramsay joined the Blues in 2008 as an eight-year-old and was part of a strong youth side that rose through the ranks.