Manchester United have made “a substantial bid” for Crystal Palace right-back Aaron Wan-Bissaka, according to Sky sources.
United need a long-term replacement for Antonio Valencia and have targeted the England U21 defender.
Wan-Bissaka has three years remaining on his contract and Crystal Palace do not want to sell, but their resolve could be tested by a big offer from United.
The 21-year-old made his Palace debut in February 2018 and became a first-team regular this season, making 39 appearances as the team finished 12th in the Premier League.
United have been already been busy ahead of the opening of the transfer window on June 11, with a deal agreed in principle for Swansea winger Daniel James.
Juan Mata has been offered a new contract but Ander Herrera and club captain Valencia were released.
United begin their pre-season against Perth Glory on July 13 and will remain in the city for a friendly game against Leeds United four days later.