Academy graduates Sam Gallagher and Harrison Reed were at the centre of a milestone moment for Saints last weekend.

The promising 18-year-olds were both unused substitutes in the 2-0 defeat at the Emirates Stadium.

Saints manager Mauricio Pochettino insists it was invaluable experience for them to be part of the first-team set-up for such a high-profile fixture.

“It’s very important for them to actually be part of the team and be on the bench,” said Pochettino.

“It’s very important as well that they slowly progress and slowly get into the first team.

“It’s also very important that they learn the atmosphere of the Premier League, of the senior side, and it’s very important overall for the future.”

Gallagher, a striker, and Reed, a midfielder, have already made their Saints debuts this season, in the Capital One Cup.

Scotland under-19 forward Gallagher, who joined from Plymouth when he was 16, was also an unused sub in the club’s 4-1 home win over Hull earlier this month, while Reed’s appearance on the bench at Arsenal represented the first time he was part of a matchday squad in the league.

Obviously, their presence was partly due to the absence of Gastón Ramírez, who only returned from international duty with Uruguay the day before the match, as well as the late withdrawal of Dejan Lovren through illness.

In addition, midfield pair Jack Cork and Guly do Prado were both injured.

However, Pochettino has already confirmed that he is happy to put his trust in the teenagers.

“(Gallagher) is a player that has been with us for quite a long time already, as is the case with Harry Reed,” he explained.

“It’s nothing new for us, as is the case with other players involved in the first team.

“We fully expect them to be part of the first team.”

Saints’ success in the first third of the season has led to a great deal of attention being paid to the work and philosophy at St Mary’s, particularly in relation to bringing through academy players.

While the club have spent big since returning to the top flight – their outlay on transfer fees since winning promotion in 2012 is about £70m – they have also built on the foundation of homegrown talent.

A total of 12 academy graduates have featured in the first-team squad at some stage this season, with captain Adam Lallana, Luke Shaw and James Ward-Prowse playing a pivotal role in the impressive start to the campaign.

While the quality of young players being produced in England is sometimes lamented, Pochettino believes there is actually plenty of ability in the youth ranks – clubs just need to give it a chance.

“There’s great talent in English football academies, as much as in Spain, Brazil or Argentina,” he said.

“It all comes down to individual decisions. Every club makes their own decisions.”

Saints’ decision has been to trust a number of those players, and Pochettino has already indicated that the emergence of the latest crop of youngsters will reduce any need to spend money when the transfer window opens in January.

“We have a lot of young players coming from the academy that are pushing really hard,” he said.

“They are making a case for being in the senior team. Players like Sam Gallagher and Harry Reed, very exciting players.

“So, in that sense, we are not worried about the depth of our squad because we have a lot of young players that guarantee us a very good future in the immediate future.

“We are covered in that sense, so we are not worried.”

Of course, clubs cannot simply throw any old bunch of youngsters at their first-team and expect success.

The players have to be talented enough in the first place.

In that sense, Saints can be grateful for the work of not just their current regime, but those who went before them and did such a good job of identifying and developing some of the players who are now thriving.

“It makes me very happy,” said Pochettino of the academy’s health. “I fully believe in the future of this academy.

“I’m also very happy and proud for the people that have been part of the academy all these years because all the work they have done now is actually being seen.”