Midfielder Victor Wanyama thanked the Southampton fans as he completed a move to Premier League rivals Tottenham.
The Kenya international has agreed to join former boss Mauricio Pochettino in north London on a five-year contract.
The midfielder becomes the club's first signing of the summer as they look to reinforce their squad for another Premier League title tilt after finishing third last season.
It is not the first time that Spurs have shown an interest in Wanyama after they failed to convince the south-coast club to sell one of their star players last summer, a decision that reaped rewards as he helped the Saints claim sixth place, guaranteeing Europa League football.
However, with only one year left on his contract, Southampton have decided to cash in on the 24-year-old.
Press Association Sport understands Tottenham will pay around ?9million up front for Wanyama, but the deal could reach almost ?12m if additional clauses are met.
Wanyama made 85 league appearances for the south-coast club, scoring four goals.
Wanyama, who moved to Southampton from Celtic in 2013, paid tribute to the club's supporters on his personal website.
"I write to you with a heavy heart to announce that I will be leaving Southampton Football Club," he said in an open letter. "As you can imagine it is very emotional for me to say goodbye to the club that gave me the chance to be the first Kenyan to play in Premier League.
"Firstly, I would like to thank the most important part of every club, the fans. It took a while for me to win you all over but I can truly say that with your support and affection I have grown as a player and a person.
"You guys have always been there to lift us up when we were down, and to celebrate with us when we were playing well. I feel really proud that I got the opportunity to wear the Southampton shirt.
"I will never forget my time in Southampton Football Club, I will keep the club forever in my heart."