Southampton captain James Ward Prowse was left out of the squad for Tuesday's friendly amid interest from West Ham.
The Hammers have cash to splash after Declan Rice's £105million departure for Arsenal and are keen to bring the midfielder back to the Premier League following Southampton's relegation.
The reigning Europa Conference League champions have made an initial £25m opening offer to the south coast side and are waiting for a response.
But his omission from the squad on Tuesday night has been put down as a precautionary measure after injuring his knee.