She will be singing Whitney's huge hit I Will Always Love You during the "In Memoriam" segment, which is sure to bring the tears in the audience.
In fact, we doubt there will be a dry eye in the house.
During today's rehearsal, Jennifer was "having a hard time" with keeping herself composed while singing the tribute to Whitney.
A Grammy crew member said that she was "crying and had to keep pausing" to collect herself, "especially on the second run-through."
It's going to be SUCH an emotional night, but we're really looking forward to see how all the artists pay tribute to the legendary Whitney tonight.
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[Image via WENN.]