Questlove reveals he and his then-bandmates, rapper Black Thought and beatboxer Rahzel, were feeling a left out after attending the prestigious music ceremony and he found himself questioning whether "all the sweat and blood" was worth it.
It was only after bumping into Williams in an elevator that he realised how far the acclaimed hip-hop group's reach had been as he learned the Good Will Hunting Oscar winner had become a big fan of theirs through his eldest son, Zachary.
The unexpected encounter was enough to convince Questlove to continue doing what he does - and the drummer will never forget it.
Shortly after news broke of Williams' death on Monday (11Aug14), Questlove took to his Instagram.com blog and shared the little-known story, revealing, "Robin Williams made such an impact on me and didn't even know it."
He went on to explain how he felt like "no one really cares all that much for us except for a select few", and continued, "This particular Sunday we were walking backstage and had to ride the elevator to the backstage area and we piled inside when suddenly this voice just said 'questlove.....black thought....rahzel....the roots from Philadelphia!!!!'
"That's right, you walked on this elevator saying to yourself, 'Ain't no way this old white dude knows my entire history and discography (sic)'....we laughed so hard. That Never happened to us before. Someone, a legend acknowledged us and really knew who we were...
"man it was a small 2 min (minute) moment in real life but that meant the world to me at the time.
"Everytime I saw him afterwards he tried to top his trivia knowledge on all things Roots associated. Simply because he knew that meant everything to me. May his family find peace at this sad time. I will miss Robin Williams. #Rip."
Williams committed suicide at his California home at the age of 63.