Ali's shorts are expected to be sell for more than $6 million (€5.5 million).
The auction of the Muhammad Ali's shorts from an iconic fight comes as Sotheby's has decided to auction off a bunch of sporting items.
Bids have been arriving online since March 27, and the auction is open until April 12.
The white shorts with black stripes have an inscription by Ali's assistant trainer and corner man, Drew "Bundini" Brown and are signed by Ali in black Sharpie.
Why are the 'Thrilla in Manila' shorts iconic?
The trunks were worn by Ali during his monumental boxing match against Frazier in October 1975 in the Philippines.
The bout was the third and final one fought between Ali and Frazier and brought Ali a historic win in what is considered the greatest trilogy in boxing history.
The fight saw 14 rounds before Frazier's coach threw in the towel.
"It was like death. Closest thing to dying that I know of," Ali had said of the fight, which was held amid stifling heat and humidity, with temperatures heightened by TV lights.
US fighter Ali was not only a boxing champion but also a vocal civil rights activist for African Americans. He died in 2016.
