Ralph Hasenhüttl praised the impact of the youngsters, as goals from Will Smallbone and Jake Vokins saw Southampton into the next round of the FA Cup.
Second-half goals from Smallbone and Vokins, both on their first starts for the club, ensured Saints a safe passage into the fourth round with a 2-0 victory over Huddersfield Town.
After a busy festive period, it's now five unbeaten in all competitions for Hasenhüttl's side, which included ten changes to the team that beat Tottenham on New Year's Day.
"I’m happy for them to help us bring us into the next round," said Hasenhüttl. "We’re all happy for them. It was the most important thing today, to have a serious performance to take the game seriously because it’s a very important competition for us.
"Sure it wasn’t always perfect and you couldn’t expect that. But all the players are playing fantastically and I think they did a good job today.
"The young lads scored, still showed they have a few deficits we need to work on. But it was a good afternoon for us because we’re in the next round, it’s what we wanted to do.
"Finally after a busy Christmas period it’s a nice finish."
Saints' changes for the game meant that many of the first-team regulars were rested, giving the likes of Shane Long, Ché Adams and Oriol Romeu the chance to take to the field.
"It’s important for them to get 90 minutes. You could see that it was not so easy for everybody. A few did better, a few you could feel were a little bit missing in terms of game experience.
"After these games we nearly played with the same team but there was no chance we could give them another game for them because we invested so much in last week.
"I didn’t expect everyone to play fantastic today, they did it really good and tried to bring a good effort which is what I’ve expected. So I am absolutely happy.
"We have a week now for Leicester. It’s important to keep the sessions short, intense but not too long. We invested a lot in the last weeks. But I think the Christmas period was successful for us and we are looking forward to the next games."