Virgil van Dijk is training on his own after telling Southampton boss Mauricio Pellegrino he wants to leave the club.
The Netherlands centre-half was a target for Liverpool earlier this summer, but the Reds withdrew their interest after Saints complained to the Premier League.
Southampton maintain van Dijk is not for sale, and Pellegrino has excluded the player from pre-season until he can demonstrate his commitment.
“The boy said that he is not available to play because he wants to leave,” Pellegrino told BBC Radio Solent. “This is the decision.
“I had to say, ‘If you don’t want to be involved because you don’t feel okay then you have to train alone until this period of time is over.
“He is not involved with the team because psychologically he is not 100 per cent. I need to work with the players who are 100 per cent to defend Southampton. It’s easy for me.”
Asked if van Dijk could get the move he is after, the Argentine said: “I repeat that the club said not. I hope that Virgil can review his feelings because you know that today a player is big business. Not just the player but behind them is a lot of interests.
“I don’t want to say too much but we need the player, 100 per cent. I want to help the squad, I want to help Virgil, but we need a player, and I repeat, involved in every training session, not just with the body but with the mind on the pitch with the rest of the players.”
Van Dijk, 26, has five years to run on the contract he signed last summer, 12 months after arriving from Celtic.