The Saints do not want to lose Van Dijk midway through the season and expect to keep him until the summer, despite interest from leading Premier League clubs.
Manchester City are believed to have shown the strongest interest in the 25-year-old centre-back, with Liverpool, Chelsea, Manchester United and Everton all monitoring his situation.
But Southampton sources are adamant the club have no intention of selling Van Dijk in the January transfer window due to the difficulty in signing a potential replacement. The Saints are believed to be ready to deter any enquiries with a £45m asking price that would more than triple the Dutchman’s cost when he arrived in September last year.
City may still test Southampton’s resolve as manager Pep Guardiola looks to solve his defensive problems, while Chelsea boss Antonio Conte is desperate for proven reinforcements to fit into his back three and has sent scouts to watch him in action.
Liverpool manager Jurgen Klopp is a known admirer of Van Dijk and in the market for a centre-back but Manchester United appear to have decided to move instead for £38m-rated Benfica defender Victor Lindelof.
Van Dijk is understood to be keen on a move to a major club in the new year, especially with several Premier League title contenders in the frame for his signature and looking to bolster their defensive options.
The Dutchman is said to be confident that he can step up a level and replicate his superb form for Southampton, who have the third best defensive record in the Premier League this season.
To that end, there is concern at the club that he recently changed agents, suggesting he may be eyeing a transfer away from Southampton less than 18 months after his £13m transfer from Celtic.
Van Dijk has established himself as one of the most impressive central defenders in the Premier League but Southampton have a buffer in negotiations after the player signed a new six-year contract in May.