Victor Wanyama posted a thank you message to Southampton fans following his reported £11million switch to Premier League counterparts Tottenham.
Wanyama, 24, joined Southampton from Celtic in 2013 for £12.5m but had just 12 months left on his deal at St Mary's Stadium.
The Kenya international made 97 appearances in his three years at Southampton, helping the club to eighth, seventh and sixth-place finishes in the league.
Wanyama wrote a message to Southampton fans to thank them for their support, while also clarifying comments circulated in the media in the lead-up to his transfer, where he will link up with former Saints boss Mauricio Pochettino at White Hart Lane.
"I write to you with a heavy heart to announce that I will be leaving Southampton Football Club," he said via his official website.
"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. I want to reassure you that any "quotes" you have read about in the media before my move was announced are false.
"I would never disrespect you by talking to the media before I have talked to you guys. 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."
He added: "Secondly, football is a team sport and it wouldn't be right not to thank my amazing team-mates. [Captain] Jose [Fonte], thanks for leading the team and always being there to pick us up when we needed encouragement. Thanks to the rest of the team for always giving 100 per cent effort, I will miss all of you.
"I also want to thank every member of the Southampton staff: those who work behind the scenes and never get credit for their contribution to our success on the pitch. We are nothing without you."