Russell Martin was sacked as head coach of Southampton following the team's disappointing start to the Premier League season, which culminated in a 5-0 defeat against Tottenham Hotspur on Sunday.
The 38-year-old departs with the club bottom and already nine points from safety having taken five points from 16 games.
"We can confirm that we have taken the difficult decision to part ways with our men's first team manager, Russell Martin," a statement read.
"Going into the start of the season, we all knew the challenges that we would face this year as we readjusted to life in the top flight, competing in the best and most competitive league in the world.
"However, the reality of our situation is clear. The board have supported Russell and his staff and been open and transparent regarding our expectations. We have all been on the same page in recognising the urgency of needing results to improve.
"We would like to take this opportunity to thank Russell and his staff for all the hard work and dedication they have given the club on and off the pitch over the last 18 months. Everyone connected with Southampton FC will always have fantastic memories of last season, especially the play-off Final win in May."
Martin was appointed as head coach in June 2023 and led the club to promotion to the Premier League via a 1-0 win over Leeds United in the Championship playoff final in May.
However, he hinted at the pressure he was under following the defeat against Spurs, which saw Southampton 3-0 down after 14 minutes.
"I didn't recognise our team in the first half," Martin said. "But I am pleased they stuck out in the second half. At this point, it is about pride and showing some care for each other."
Martin guided Southampton to promotion last season playing an eye-catching style that earned him plaudits.
But his refusal to bend from his tactics has seen his side become far too easy to beat in the top flight.
Asked about the boos at the end, he said: "[The fans] were amazing in the second half. Really good.
"As a person [the boos don't hurt]. Because I understand that it's not personal. But as a manager, yes. It hurts me as well as the team. But I also understand it."