It is claimed that Palace have agreed a fee of around £20 million, including add-ons, for Chambers, but De Boer is not ready to finalise the deal until he finds out if United will loan him Fosu-Mensah.
Timothy Fosu-Mensah of Manchester United (left)
Watford have also been linked with a move for Fosu-Mensah, but De Boer's relationship with the former Ajax defender he worked with during his time in charge at the Amsterdam ArenA could work in Crystal Palace's favour.
De Boer is said to want a right-sided defender to team up with Scott Dann and Jairo Riedewald - another former Ajax player - in his 3-4-3 system.
And should 47-year-old see of Watford to sign the Manchester United talent, it is claimed he will drop his interest in Chambers and spend the £20 million elsewhere.
Can Crystal Palace beat Watford to the Manchester United man's signature?
Calum Chambers in action for Middlesborough