As Jannik Sinner wonders whether he could still be banned for failing two doping tests, a players' association is asking the Grand Slams and two main tours to pay for a legal defence fund for athletes.

The Professional Tennis Players Association (PTPA) was created in 2019 and aims to increase player power within the sport.

It believes the four majors, the men's ATP Tour and women's WTA Tour should fund access to third-party lawyers, so financial resources are not a barrier to a speedy and authoritative defence.

It would - they argue - make the system fairer for all players regardless of their ranking.

The PTPA was co-founded by Novak Djokovic, who raised this topic at the recent US Open.

"The question is whether a player can afford to pay a significant amount of money for a law firm that would then more efficiently represent his or her case," he said.

"I feel like we have to collectively investigate how we can standardise everything so that every player, regardless of his ranking or status or profile, is able to get the same kind of treatment."

Some players have raised questions about the speed in which a resolution was reached in Sinner's case.

World number one Sinner twice tested positive for the steroid clostebol in March, but was cleared of fault or negligence by an independent panel.

The World Anti-Doping Agency (Wada) has lodged an appeal against the decision to clear the Italian of blame, believing the independent panel's findings were "not correct under the applicable rules".

It has asked the Court of Arbitration for Sport (Cas) to set aside the decision and ban Sinner for between one and two years.

Ahmad Nassar, the PTPA's executive director, told BBC Sport in an "ideal world, every player would have resources available to him or her, whether or not they can afford it".

But he argued his organisation should not have to foot the bill.

"Not right now, given our size and our structure," he said.

"The four Grand Slams and the two tours - why don’t they fund a legal defence fund for the players to be able to tap into?

"They provide players' prize money and benefits and pensions. Why wouldn't you provide them access to third party lawyers who are not on staff?

"That is certainly something we would push for, and versions of that certainly exist in some other sports.

"Set up a legal defence fund, we are happy to administer it, but we are really four years old and I think it's an unfair burden to put on either the PTPA or the players themselves directly."

BBC Sport has approached the Grand Slam Board, the ATP and WTA Tours but none of them wanted to comment.

The PTPA says it was set up to "support, protect and advance players’ well-being on and off the court".

It has so far had a fractious relationship with tennis' established powers and has not been able to get into the room where key decisions are made.

Nassar said he thinks the system is "patently unfair to every player, Jannik included" and highlighted the case of Britain's Tara Moore.

Moore was Britain’s leading women's doubles player when she was provisionally banned for testing positive for nandrolone and boldenone in May 2022.

She was cleared by an independent tribunal in December 2023, but 10 months later is still waiting for the ITIA's appeal against that decision to be heard by Cas.

"I have many reservations about how every single one of those cases is handled," Nassar continued.

"In Tara, here is a player who won her appeal, and certainly wasn't the number one player in her sport, but she still missed 18 months.

"She's still dealing with an appeal and fighting to get her reputation back. There is no winning in that case."

Wada's appeal against the Sinner verdict may well be heard more quickly.

An appeal by the former world number one Simona Halep was heard just over four months after it was registered, with the verdict issued by Cas a further month after the hearing.

It was, however, only last Thursday that the panel's full reasoning was published.

Cas cut Halep's suspension for testing positive for roxadustat from four years to nine months but concluded that despite steps actively taken by her to ascertain the contents of the supplement, considered the fault of the negative test, "there was fault on the player’s part".

Wada will also be hoping to prove fault or negligence on Sinner's part.

The initial tribunal decided Sinner was inadvertently contaminated with clostebol by his physiotherapist, Giacomo Naldi, who had applied an over-the-counter spray containing the banned substance to treat a cut on his own hand.