There has been plenty of anticipation regarding Gunn's Saints bow. He arrived in the summer despite Alex McCarthy enjoying a fantastic spell once he wrestled the number one spot off Fraser Forster, and went into this week still awaiting his first appearance for Mark Hughes' side.
However, he was one of a number of players to come into the team for the trip to the Amex Stadium, and he tasted victory on his debut as Charlie Austin scored the game's only goal with penalties looming.
Gunn did not have a lot to do against the Seagulls, but he did produce a fantastic stop during the early stages of the second-half to deny Victor Gyokeres breaking the deadlock in what was undoubtedly a largely drab affair.
And given that he did not have a lot to do, he may well be pleased with the reaction from some of the Saints supporters on social media after Hughes' men booked their spot in the next round.
The fans are not yet getting carried away and suggesting that McCarthy needs to be kept out of the side after Gunn's performance, but there is plenty of optimism about the man pushing the current number one at St Mary's this season.
Here are some of the comments regarding the former Manchester City ace's debut...
Angus Gunn eventually needs to get more game time than just cup games. Some league experience will also do him good. He’s been good from what I’ve seen of him. #SaintsFC— Nathan Newington (@newington13) August 28, 2018
Played well: Gunn. Solid, played pretty well: Bednarek, Yoshi, JWP. Top effort: Gallagher. Game changer: Redmond. Final positive, 2080 #saintsFC fans backing all the players, including those off form.— matt (@SaintMadDogMatt) August 28, 2018
Old Benjamin Button in goal got proper rattled especially by the lads behind the goal to the left! #SaintsFC last 20 very enjoyable- Gunn & Targett great games & the 3 subs were good!— Philip Binns (@Binnsphilip) August 28, 2018
Really good performance from you tonight See u soon in the starting 11.— Wiesel (@Wiesel_11) August 28, 2018
Actually think @AngusGunn01 is our future No1 and could potentially replace @Alex_Macca23 by the end of the season . Remember what happened to Fraser last season? Good to have completion & in #davewatson we have one of the best coaches to keep them on their toes— Ruth Alice Pollock (@RuthiePollock) August 28, 2018
Lots of good things too take away from this result! First start for @AngusGunn01 clean sheet✔ @chazaustin10 is up & running⚽, played some great stuff at times and us #SaintsFC fans were class if i say so myself.. Long trip home now! A happy one mind☺☺ @SouthamptonFC #bhafc pic.twitter.com/SEAbYK2kj3— DannyFord1 (@SaintDan9) August 28, 2018