The pictures at St Mary's tell a story. Or rather, they tell of the club's eagerness to create a new story. At the start of this season most of the photographs adorning the walls inside the stadium were replaced; out went many of the reminders of old glories, in came huge shots of the club's young thrusters, each image emblazoned with enormous, portentous captions declaring "Our Time Is Now" and "Our Dream is Real".

The message is clear: Southampton believe they are on the verge of something special. They are starting to convince the rest of the country.

Their ascent has been spectacular. This emphatic win over Fulham extended the club's best start to a top-flight campaign and means they have soared from the third tier of English football to third in the Premier League in only three years. The money invested by the Liebherr family has helped but the rise of the Saints is down to more than that: it is also thanks to expert youth development and, since last January, the uplifting management of Mauricio Pochettino.

The Argentinian had a difficult act to follow when he was appointed after the dismissal of Nigel Adkins, who had guided the club to successive promotions, but he has vindicated the faith put in him by the chairman, Nicola Cortese, by turning a decent team into one who are exceptionally dynamic, wonderfully enterprising and increasingly confident. "All the players have improved since I have been here," Pochettino said. "It is very satisfying for me to see their evolution in 10 months."

The most obvious difference is reflected in the team's defensive record – after nine league games last term Southampton had conceded 26 goals; at the same stage this season they have let in only three, making them the meanest team in the league.

Dejan Lovren, the centre-back who has forged a solid partnership with José Fonte since joining from Lyon in the summer, said that Pochettino, himself a former international defender, has been inspirational. "He gives us a lot of advice because he's an intelligent man," he said.

"Really I have a learned a lot from [Pochettino]. I didn't expect that I will learn something like this. We keep the line very high and I never play like this before. It's a little bit with risk but I think we do a very good job. Each day we talk a lot. Our philosophy is when we lose the ball we need to get it back very quickly. You saw that against Fulham, we lost the ball in the first half and they didn't have a chance to do anything. It was amazing."

Winning the ball back quickly starts with the striker. Against Fulham, Rickie Lambert, who scored the first goal and teed up the second for Jay Rodriguez, defended with as much zeal as he attacked. "The first line of defence when we don't have the ball is Rickie Lambert, so we are all defending at the same time, wanting to keep possession and when we don't have it we are crazy to get it back," Pochettino said. "It is all about the collective work."

Such has been Southampton's defensive improvement that Fonte has been tipped for a call-up to the Portugal squad for the World Cup play-off against Sweden. Similarly, there are suggestions in France that the midfielder Morgan Schneiderlin deserves a place in their team, while, of course, there is an array of talent at the club that Roy Hodgson could take with England to Brazil.

Lambert was one of six Englishmen who started the rout of Fulham and the others are all much younger, including the teenagers Luke Shaw and James Ward-Prowse, fruit of the club's academy. At a time when England are fretting about their ability to cultivate youngsters, the performances this season of the likes of Shaw, Ward-Prowse, Adam Lallana and Calum Chambers suggest Southampton could teach the FA a thing or two.

"It was clear from the beginning when Nicola Cortese called me that we were going to focus on the academy, strengthen it and use as much as we can from it," Pochettino said. "I am a full believer in the philosophy to push up through the young players and am a keen supporter in nurturing them and make sure they come through the ranks and being part of this club."

Pochettino is aware that if Southampton continue to thrive, bigger clubs may seek to prise away their prized youngsters, as happened with Gareth Bale, Theo Walcott and Alex Oxlade-Chamberlain. "That is something that is out of our hands," he said. "We cannot avoid other clubs being interested in our young players. We will do as much as we can to make sure they are here for a very long time."

Playing like this will make it very hard for anyone to leave and could enable Southampton to take one of those big clubs' places in the Champions League.

Man of match Jay Rodriguez (Southampton)