Costa has made it known that he wishes to return to Atletico.
Reports from Spain suggest that Bundesliga duo are being closely tracked by La Liga giants.
L'OM president Jacques Henri Eyraud is a huge fan of the fiery Spaniard.
Multiple clubs were interested in Perez but Deportivo boss Pepe Mel expects him to return to Spain.
"Someone might if they have the money and want to spend it," says Manchester City boss.
Dembele has gone on strike to force a move to Barcelona this summer.
Los Blancos began the defence of their La Liga title with 3-0 win at Deportivo La Coruna on Sunday [20 August]
Messi, 30, is yet to put pen to paper on a new four-year contract at Barcelona.
Arsenal, Liverpool and Tottenham target seen as an alternative to Paris Saint-Germain's Marco Verratti.
Radio station Onda Cero claim that Atletico will pay an initial €45m with another €10m in add-ons.
Asensio's current deal at Real runs down in 2022 and earns £3.2m-a-year.
Brazilian centre-back has penned a five-year contract in Spain that includes an €80m buyout clause.
De Gea has two years left on his contract at Old Trafford.
Mina will join Barcelona in January after completing the 2017 Brazilian league campaign.
Gabriel joined Arsenal from Villarreal during the January transfer window in 2015.
Coutinho and Dembele have emerged as transfer targets for Barcelona.
General manager Pep Segura claims deals for Dembele and Coutinho are close.
Fiery forward believes situation will be resolved upon his imminent return to Spain.
Barcelona have had bids rejected for Coutinho and Dembele by Liverpool and Dortmund respectively.
Reports in Italy claim Napoli swiftly turned away an offer from Ernesto Valverde's side.
Liverpool and Dortmund have already rejected bids for their star players.
Dembele is pushing for a move to Camp Nou and is currently suspended after skipping training.