World No 1 Jannik Sinner twice tested positive for the banned steroid clostebol back in March, with news of the violations made public in August.
The 23-year-old was found to be of "no fault or negligence" by the International Tennis Integrity Agency [ITIA] in their ruling and was not handed a suspension, though was stripped of ranking points from Indian Wells.
However, the World Anti-Doping Agency [WADA] confirmed last month that they were appealing the ITIA's verdict to the Court of Arbitration for Sport [CAS].
A ruling is expected early next year and should CAS rule in WADA's favour, Sinner could face a suspension of up to two years.
Sinner's case has attracted huge attention since it emerged three months ago, and now his Davis Cup captain Volandri has spoken out in his defence.
In quotes reported by QS Sport, Italian Davis Cup captain Filippo Volandri revealed he did not "even want to think" about the possibility of the world No 1 being banned.
He said: "I don't even want to think about a possible disqualification of Sinner, given his honesty and the irrefutable evidence he has provided.
"But if there is a person with broad shoulders it is Jannik. A disqualification would be the greatest injustice in history."
Volandri's comments come just days after Italy sealed a third Davis Cup triumph, becoming the first nation since the Czech Republic (2012-13) to successfully defend the title.
Sinner again played a starring role in 2024, winning the decisive rubber versus Tallon Griekspoor to seal a 2-0 victory against the Netherlands in Sunday's final.
The Australian and US Open champion is far from the nation's only current star, with Volandri able to call on the likes of Matteo Berrettini and Lorenzo Musetti to represent their country.
The former world No 25 admitted it was difficult to limit his squad to a maximum of five players amid the nation's strength and depth.
"My choices? It's not easy to make them, it will always be the most difficult part of my role," added Volandri.
"We were the first to work with a psychologist too. It was hard for me to leave [Matteo] Arnaldi and [Flavio] Cobolli at home or tell Musetti that he wouldn't play against Australia. He was disappointed, in the days before he had had amazing tennis.
"This is a group of friends, they are ready to be there when someone else needs them. I want the national tennis team to stay at the top for a long time: this does not mean winning every year, but always staying among the top."
