The undefeated American boxer has sent out a strong warning to the Filipino boxing legend ahead of their clash at the MGM Grand in Las Vegas.
The two welterweights will come to blows on July 20 and Thurman is eager to write his own legacy by dropping the boxing icon to the canvas.
Thurman (29-0-0) is 10 years younger than Pacquaio (61-7-2), but the American knows better than to write off the eight division champion.
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"This is a once in a lifetime opportunity to destroy a legend and create my own legacy," Thurman said on a conference call, as per AFP.
"How can I not Babe Ruth it and step up to the plate, point and start swinging. How can I not go for it? I've got an '0' and I'm not afraid to let it go.
"If Manny Pacquiao is the man that beats me, he's the man that beats me. I'm going to shake his hand after the fight and congratulate him.
"It is what it is. But when Keith Thurman steps into the ring, you're dealing with Keith Thurman. And he's a bad man," he concluded.