The fighter was preparing for his upcoming rematch with welterweight champion Timothy Bradley at coach Freddie Roach's Wild Card Boxing Club when the Lay Lady Lay singer, a longtime boxing fan, phoned and asked if he could stop by with a friend.
Pacquiao's spokesman Fred Sternburg tells RollingStone.com, "I've never seen the place take an aura like this, and I've been going to that gym for nearly a decade. We were all awestruck.
"Manny sparred eight different rounds with two different fighters while Dylan was there. He stayed for an hour and sat on a bench that you'd use to lift weights. Before and after the sparring, Dylan posed for photographs with anyone that asked and signed autographs... He accommodated everybody and smiled the whole time. But, my God, it was Bob Dylan! It was like seeing one of the apostles."
Even Pacquiao got in on the action, tweeting a photo of himself with the singer/songwriter.
He wrote, "After Bob Dylan watched me train today, Freddie Roach said, 'I think a hard rain's a-gonna fall on Timothy Bradley'," referring to one of the singer's classics.
Pacquiao will be hoping the visit from Dylan will bring him luck when he steps into the ring with Bradley in Las Vegas on 12 April (14).