Mauricio Pellegrino has been appointed as the new Southampton manager on a three-year deal.
He replaces Claude Puel, who was sacked last week after frustrations behind the scenes and in the stands, despite guiding Saints to eighth in the Premier League and the League Cup final in his first season.
Southampton have acted quickly to name his successor, with former Alaves boss Pellegrino penning a contract at St Mary's less than a month after stepping down as boss of Alaves.
Pellegrino ensured Alaves had a memorable first season back in La Liga, leading them to a ninth-placed finish -- beating Barcelona, Valencia and Villarreal along the way -- as well as to the Copa del Rey final, where they lost 3-1 to Barca.
"I am really happy to become the new coach of Southampton Football Club," Pellegrino said. "The club has a great reputation for having a strong and stable structure, competing in the Premier League and playing attractive football.
"I think my philosophy and the culture of the club will work well together. We have to be a team on and off the pitch; I want to make the supporters proud of the players and to feel part of the game every week.
"I want to win matches, be successful and develop a team spirit where everyone gives 100 percent and supports each other.
"I am excited and passionate about what the future holds for us and look forward to meeting the players and beginning our preparation for the new season."
Southampton were looking for a manager who would embark on a long-term project to try and take them into the top six of the Premier League on a regular basis, sources close to the club told ESPN FC earlier this week.
Saints were keen to avoid a repeat of managerial appointments in recent years when Mauricio Pochettino and Ronald Koeman left following successful spells at the helm.
Sources said Pellegrino's experience of English football from his time working alongside Rafael Benitez as an assistant at Liverpool was also viewed as positive.
"We had an impressive list of candidates and went through a comprehensive interview process," said Saints vice chairman Les Reed. "Mauricio impressed us throughout with his depth of knowledge, motivation and ability, communicating this in a professional and passionate way.
"He has an excellent understanding of the Southampton way, and his style of play and aspiration matches the philosophy, culture and ambition of the club.
"We firmly believe Mauricio is the right person to help us take the next steps. He knows our players and believes we have a great squad that with some fine-tuning will be able to deliver continued success.
Pellegrino becomes Southampton's second Argentine manager, with Mauricio Pochettino previously at the helm.
The 45-year-old, a former international defender, will officially join up with the club next week, in time for the start of preseason training.
Pellegrino played for Barcelona, Valencia and Liverpool, while his coaching career has included stints in charge of Valencia, Estudiantes and Independiente.
Information from Press Association was used in this report.