Cesc Fabregas has received assurances about his future from boss, Antonio Conte meaning that the 30-year-old attacking midfielder is to stay at The Bridge for at least another season, throwing Matic's future in the air.
The 22-year-old French global was in fantastic form in Monaco's title winning campaign.
The 22-year-old was at the heart of Monaco's midfield in their UEFA Champions League semi-final run and Ligue 1 triumph last season and now it looks as though he will be a Chelsea player shortly.
Bakayoko uploaded a photo to his social media accounts on Friday of the Chelsea training pitches, with the caption "soon".
An earlier report from BBC Sport suggested that the player could undergo a medical in west London this week ahead of inking a five-year contract on a sizeable wage package.
Chelsea have made just two signings so far this season, capturing Willy Caballero on a free transfer before landing Antonio Rudiger from Roma for £34m.
Bakayoko is now recovering from a knee surgery which may rule him out the start of the season.
Costa, who endured a fractious relationship with Conte last season, is linked to a move back to Atletico Madrid even though the Spanish club can not register new players until January because of a blanket Federation Internationale de Football Association transfer ban.