Former welterweight boxing champion Keith Thurman blasted Top Rank founder and CEO Bob Arum in an Instagram post on Thursday.

"F--k Top Rank. F--k Bob Arum…you piece of s--t," Thurman said, per Sean Crose of Boxing Insider.

"All of your great fighters left your ass. Thurman ain't no punk."

He then added, in regards to he and other PBC fighters: "You can't afford us, Bob. You ain't gonna pay no full price [during the pandemic], but you ain't getting a discount."

Thurman continued, referencing the decreasing potential of a fight between he and welterweight champion Terence Crawford, which the boxer has pursued.

"Stop talking s--t. There ain't going to be no fight. You can't afford it."

"I don't need ten million dollars," he added. "But I do need respect."

He continued: "Terence Crawford wanted to fight me last year. Thurman vs. Crawford is fire, they can't afford it."

Thurman has made it clear that he's interested in fighting a pair of welterweight champions in Errol Spence Jr. or Crawford.

"Crawford knows that he can get it," Thurman told boxing ring announcer and play-by-play commentator Ray Flores (h/t Mark Lelinwalla of DAZN) last April. "I'm a very simple, simple man when it comes to the fight world and doing business. Be real, send the contract, watch me sign it."

He added, per Lelinwalla: "If I'm presented with both at the same time, I'd go Spence over Crawford. Spence has a priority over Crawford. At the end of the day, he has two belts."

Arum said earlier this month that a representative from Thurman's camp reached out to him about setting up a fight with Crawford, per a conversation with Frederick Hawthorne of Barbershop Conversations (h/t Albert Craine of Boxing News 24/7).

"He'd been in touch with me before, and now he was calling me again," Arum said.

"He said, 'Keith would be interested in fighting Crawford,' and I said, 'Give me the terms that you want, and let's see if we can do it.'

"That was a couple of days ago, and I assume I'll hear back from him."

Hawthorne asked Arum if Thurman's camp wanted $10 million. Arum never directly said yes in response but noted that he would have trouble finding half that figure for a Thurman-Crawford fight.

Thurman, 32, is 29-1 lifetime. The former WBA champion lost his first match to Manny Pacquiao in July 2019.

Spence, 27, is the unified welterweight champion, sporting a 27-0 record. Crawford, the WBO welterweight champion, is 37-0 lifetime.