The former Benfica man had an excellent campaign with Wolves last season, and gained a host of admirers from higher leagues.
Tottenham Hotspur and Wolverhampton Wanderers are expected to be busy in the transfer market this summer.
The Wolverhampton Wanderers man would be a superb summer addition for Newcastle United.
Wolverhampton Wanderers are said to be willing to sell Helder Costa this summer.
It is strongly rumoured that Paul Lambert left Wolves due to Mendes' transfer involvement, while new manager Nuno Espirito Santo is a Mendes client.
The Turkish side are said to be interested in the Championship duo.
Wolverhampton Wanderers will be hoping to put a largely disappointing Championship season behind them this summer.
Wolverhampton Wanderers winger Helder Costa has been linked with a move to Liverpool.
Southampton want Wolverhampton Wanderers striker Helder Costa, while Sam Gallagher is being targeted by the Championship side.
Southampton and AS Monaco are reportedly interested in signing Wolverhampton Wanderers winger Helder Costa in the summer transfer window.
Costa has excelled for West Bromwich Albion's fierce rivals Wolverhampton Wanderers this season.
Signings made by the likes of Leeds United, Aston Villa, Nottingham Forest and Sheffield Wednesday are vying to be deemed the best acquisition in January.
Wolverhampton Wanderers have completed the permanent signing of Costa for a reported £13 million.