Midfielder Andy Robinson admits he was caught by surprise when he was handed his debut for Saints' First Team on Tuesday evening.
The 19 year-old was included among the substitutes for the first time when he was named on the bench for the Capital One Cup game against Sheffield Wednesday.
And, when Jack Cork went down injured ten minutes from time, the Academy product was summoned by gaffer Nigel Adkins and introduced for the closing stage.
"It was really good," Robinson told Saints Player as he looked back on his maiden First Team appearance.
"It happened quite quickly and was unexpected, but it was great to get on. This was the first time I've even been on the bench, so to come on was a bonus.
"I'm really happy. I've been around [the First Team] a lot, and they are really great with me and the other young players."
Robinson will return to Under-21 duty on Monday afternoon as Martin Hunter's men take on their Stoke City counterparts at Staplewood.
Saints currently lead their Barclays U21 Premier League group having won two and drawn two of their opening four fixtures, leaving 'Robbo' pleased with how things are going.
"We're still unbeaten, so we're doing alright at the moment," assessed the midfielder.
"Our game (against Spurs on Monday) got called off the other day but there's a couple of games to come at St Mary's, so there's a good chance to impress there.
"I'm really happy at the moment. I had a little blip with an injury but I'm still ahead of where I thought I'd be at this stage.
"I've played the last three games and was involved [for the First Team] the other night, so it's good.
"Hopefully I'll be involved on Monday, but I never really set myself targets," he continued.
"I take everything as it comes, like the other night because that was unexpected. It's about working as hard as you can."