UNDERSTANDING THE NATURE OF THE CORONA AND DISK-CORONAL INTERACTION IS A FOREFRONT CHALLENGE. WHILE NUSTAR IS THE LEADING INSTRUMENT AT PROBING THE HIGH-ENERGY SPECTRAL REFLECTION COMPONENT NICER PROVIDES A COMPLEMENTARY VIEW OF THE THERMAL ACCRETION DISK. BOTH INSTRUMENTS HANDLE BRIGHT SOURCES WITHOUT SUFFERING FROM PILEUP EFFECTS. NICER IS CARRYING OUT A MONITORING PROGRAM ON CYG X-1 THE BLACK-HOLE SOURCE FOR WHICH DISK AND REFLECTION COMPONENTS ARE MOST STRONGLY INTERMINGLED AND WITH A DISK THAT IS COOL AND OUT OF REACH FOR NUSTAR ALONE. WE ASK FOR 6X20 KS NUSTAR OBSERVATIONS OF CYG X-1 TO BE CARRIED OUT AT ANY TIME. NICER WILL WORK WITH NUSTAR TO COORDINATE THESE OBSERVATIONS AND THE NICER ALLOTMENT IS ALREADY APPROVED.