The shorts worn by the great Muhammad Ali in his legendary 1975 boxing bout the 'Thrilla in Manila' are expected to be sold for close to $6 million at auction at Sothebys in New York next week.

Bids for the Everlast-branded white with black stripe shorts have been rolling in since March, including at least one bid of $3.8 million.

The trunks, signed by Ali, were sold for $150,000 in 2012 but are likely to fetch 40 times that sum now, according to Sothebys.

The auction is open until April 12.

Alis 'Thrilla in Manila' fight against Joe Frazier was held in the Philippines and followed his 'Rumble in the Jungle' bout in the Democratic Republic of the Congo (then Zaire) the year before.

Alis fight in the Philippines went to 14 rounds before Fraziers coach threw in the towel. The fight is considered one of the greatest in boxing history.

'It was like death. Closest thing to dying that I know of,' Ali said of the fight, which was held amid stifling heat and humidity, with temperatures heightened by TV lights. Ali, born Cassius Clay in the southeastern state of Kentucky, is known as both a sporting great and for his role in fighting for civil rights for African Americans. He died in 2016 age 74. Frazier passed in 2011 age 67.

As well as being signed by Ali, the Everlast trunks are also inscribed by his corner man, Drew Bundini Brown, who died in 1988 – they fetched just $1,000 (£800) when auctioned after his death.

In 2022, Alis WBC heavyweight belt from his 1974 “Rumble in the Jungle” fight was sold at auction on Sunday for $6.18 million, making it fourth-most expensive piece of sports memorabilia ever sold.

Auction houses are increasingly tapping into the lucrative sports memorabilia market in recent years. Six shirts worn by Argentina captain Lionel Messi at the 2022 World Cup sold in December for nearly $8 million.

A collection of six match-worn Lionel Messi jerseys from the 2022 World Cup. Photo: Sothebys

In December 2022, legendary basketball player Michael Jordans Chicago Bulls 1998 NBA Finals jersey sold for a record $10.1 million. In the same year, sneakers worn by Jordan – a pair of Nike Air 13s – sold for $2.2 million, making them one of the most expensive pair of trainers ever bought.

In May 2022, the famous Hand of God shirt worn by Argentina footballer Diego Maradona during the 1986 World Cup quarter-final against England fetched £7.1 million at auction.

The sale comes as Sothebys is auctioning off a slew of sports lots, including a uniform from NBA star Victor Wembanyama.

Despite a growing interest in historic sporting items, Sothebys said that, as of Thursday, the minimum price agreed to by the seller of Alis shorts has not yet been reached.

Also for sale is a raft of NBA jerseys, including French player Wembanyamas complete uniform from an exhibition game held earlier this year.

Interest in the game day goods also apparently extends to items from Wembanyamas locker – including a chair, water bottles and a towel.

The jersey, Sothebys estimates, is expected to sell for $80-120,000. The locker contents are estimated to go for $5-7,000.