Mauricio Pochettino said he faced a challenge to win over Southampton supporters after being appointed as Nigel Adkins' replacement.
The Saints surprisingly sacked Adkins, who had led them from League One to the Premier League and guided them to 15th place in the top flight, and almost immediately announced former Espanyol boss Pochettino as his replacement.
Southampton executive chairman Nicola Cortese said the decision had been made with the club's long-term future in mind - but it has angered fans, with whom Adkins was an extremely popular figure.
Pochettino said the "biggest challenge" he faced was to convince them that he was the right man for the job, but he believed he could do so with "honesty and hard work".
"It [coming to Southampton] happened quickly. Small details are not important - it's important I'm here at this project and club," the Argentine told reporters through an interpreter.
"They have done really well. I am a great admirer of English football and am happy to be here.
"The challenge is to be part of this project... the kindness of the supporters is the biggest challenge I have. They are the biggest part of this club and I hope I can convince them with honest and hard work."
The new manager said he was "passionate about the Premier League" and said Jose Mourinho had told him that "the best football in the world is being played here".
In a statement, Cortese said: "Whilst we acknowledge the contribution Nigel has made during the past two years, for the club to progress and achieve our long-term targets a change was needed.
"Mauricio is a well-respected coach of substantial quality who has gained a reputation as an astute tactician and excellent man-manager.
"I have every confidence that he will inspire our talented squad of players to perform at the highest possible level."
Pochettino's first game in charge will be Monday night's home game against Everton, when it seems likely there will be a show of support from the fans for their former manager.