(KRON) – The 1975 bout between boxing legends Muhammad Ali and Joe Frazier is regarded as one of the greatest fights of all time. It was the last fight in a trilogy between two of the greatest heavyweight boxers.

The trunks Ali wore on Oct. 1 at Araneta Coliseum in Quezon City, Philippines, are now up for auction. Ali’s signature white shorts with black trim are expected to sell for up to $6 million.

As of Thursday, Sotheby’s was selling the shorts at a current bid of $3,800,000. According to the website, bidding for this piece of boxing history is expected to be between $4 million and $6 million.

Bidding ends on April 12 at 9:31 a.m. PT.

Ali won the fight by a technical knockout at the end of the 14th round. The then-33-year-old fighter was famously known to have described the fight as the closest to death he ever felt.

Frazier is considered to be Ali’s biggest rival. The two split their first two fights — Frazier winning the first bout in 1971 and Ali winning the second in 1974.

Ali is regarded as not only one of the greatest boxers but also one of the greatest athletes of all time. He is considered one of, if not, the most significant sports figure of the 20th century. The Hall of Fame boxer died on June 3, 2016, at age 74.

The Associated Press contributed to this report.