CORRELATED FAST MULTI-WAVELENGTH VARIABILITY IS A POWERFUL TOOL FOR STUDYING THE PHYSICS OF ACCRETION AND EJECTION OF RELATIVISTIC JETS IN X-RAY BINARIES. USING SIMULTANEOUS X-RAY AND NEAR-INFRARED DATA WE HAVE RECENTLY SECURED THE RST UNAMBIGUOUS DETECTION OF SUB-SECOND TIMESCALE INFRARED VARIABILITY FROM A JET WHICH ALLOWED US TO ESTIMATE THE SPEED AND THE SIZE OF THE JET. OUR RESULTS FROM FURTHER DATA ALSO SHOW THE RST INFRARED DETECTIONS OF DI ERENT TYPES OF QUASIPERIODIC OSCILLATIONS (TYPE B AND TYPE C) DEMONSTRATING THAT THE PROPERTIES OF THE JET DEPEND ON THE SPECTRAL STATE OF THE BLACK HOLE. HERE WE PROPOSE TO MONITOR THE OUTBURST EVOLUTION OF A BLACK HOLE TRANSIENT WITH XMM SIMULTANEOUSLY WITH GROUND-BASED OPTICAL AND INFRARED FACILITIES IN ORDER TO APPLY THE SAME TECHNIQUE TO DI ERENT SPECTRAL STATES. FOR THIS PURPOSE WE PROPOSE TO PERFORM UP TO 10 SHORT XMM OBSERVATIONS (7 KS EACH) IN ORDER TO COVER THE DI ERENT STAGES OF THE OUTBURST. WE WILL MONITOR THE ENERGETIC AND GEOMETRICAL CHANGES IN THE JET AS WELL AS ITS RELATION WITH THE ACCRETION DISK. THESE DATA WILL OPEN AN EXCITING NEW WINDOW FOR STUDIES OF ACCRETION-EJECTION COUPLING.