Leeds have begun internal disciplinary proceedings against Charlie Taylor following his refusal to play in Sunday's Sky Bet Championship game at Wigan, it is understood.
Taylor, 23, is out of contract in the summer and head coach Garry Monk revealed after his side's 1-1 draw at the DW Stadium in the final league game of the season that the defender had made himself unavailable to travel.
Monk said Taylor was "naive" and had been "ill-advised" in his post-match press conference, adding his behaviour had been "unacceptable" and that the club would take a strong stance against it.
Leeds refused to comment when approached by Press Association Sport, but it is understood the disciplinary process is under way.
Taylor, who progressed through the club's academy after joining as a nine-year-old, had a transfer request turned down last summer after being linked with Premier League clubs West Brom, Middlesbrough and Crystal Palace.
He refused to enter into talks over a new contract - he signed a three-year deal in June 2014 - and it has been widely reported that he will join West Brom when his current deal expires.
Leeds will be entitled to compensation for the player, expected to be a seven-figure fee, as he is under the age of 24.
Taylor made his league debut for Leeds 10 days before his 18th birthday in September 2011 and has made a total of 104 appearances - 32 this season - scoring three goals.
Meanwhile, Leeds co-owner Andrea Radrizzani said he expects to complete his 100% buy out at Elland Road within the next fortnight.
Radrizzani, 42, who already owns 50% of the club's shares, has been in talks with Massimo Cellino over taking full control and told Sardinian newspaper Corriere della Sera the deal will be completed within two weeks.
"Within 10 days, at most two weeks, Leeds will be 100% (mine)," Radrizzani told the Sardinian newspaper.
Leeds confirmed last week that talks between the two parties were "ongoing and positive", while it has also been reported that Cellino will purchase Serie B club Brescia once he has severed all ties with Leeds.
Italian businessman Radrizzani bought a 50% stake in Leeds through his company Aser Group Holding in January.
It was widely reported then that Radrizzani would have the option of completing a 100% takeover at the end of the season if Leeds failed to win promotion.
Radrizzani appointed former Real Madrid director of strategy Ivan Bravo to the board at Elland Road at the end of last month.
Former Cagliari owner Cellino bought a 75% stake in Leeds from previous owners Gulf Finance House in 2014 before acquiring full control in September last year.