Welsh National Opera's former conductor has been accused of bullying its principal oboist who was sacked after more than 30 years with the company.
Murray Johnston, 61, told a Cardiff employment tribunal that Carlo Rizzi had singled him out for criticism.
He is claiming wrongful dismissal.
WNO's managing director Peter Bellingham said the player's standards were holding the orchestra back. Mr Rizzi will not give evidence to the tribunal which is continuing.
The tribunal was told how Mr Johnston, known as Sandy, was sacked in 2008 after playing for 34 years with the company.
During that time, he worked under a number of musical directors, including Mr Rizzi, WNO's musical director between 1992 and 2001 and between 2004 and 2007.
The tribunal was told that Mr Rizzi raised concerns about Mr Johnston's ability as principal oboist in 2004.
Management then told the player he needed to work on his ensemble playing, improving how he blended the sound of the oboe with the rest of the woodwind section, and then with the wider orchestra.
Mr Johnston told the hearing he felt the criticism went too far and at one woodwind rehearsal he was singled out by Mr Rizzi over a period of three hours.
He said he was then asked to re-audition for his job.
He was told this was part of normal WNO procedure if they felt a musician was not up to the expected standard but it only assessed their solo playing.
Mr Johnston told Wednesday's hearing he was "euphoric" at passing the audition but at a meeting afterwards management told him he still had to work on his ensemble playing.
The whole process from the initial complaint to dismissal took three-and-a-half years.
Bill Kerr from the Musicians Union told the tribunal Mr Johnston had "proved himself" after passing the capability test.
He said: "Unless the company had a tangible reason to doubt his ability it appeared to be a witch hunt.
"It is quite unusual for someone to go through the capability test procedure, and even more unusual for them to pass it.
"Once someone is under suspicion then that person stays permanently under suspicion and there's no way of clearing their name.
"If you are not up to the job then you are spotted pretty quickly. It wouldn't take a three-and-a-half year process."
Geraint Talfan Davies, chair of the WNO since 2006 and between 2000 and 2003, was in charge of one of the appeals made by Mr Johnston but did not take the final decision to sack him.
He said his job was to see whether the WNO had complied with its own disciplinary procedure.
Mr Talfan Davies told the hearing he spoke to a number of WNO musicians who also had concerns about the oboist's playing.
WNO managing director Peter Bellingham has denied Mr Johnston was unfairly dismissed.
He told the tribunal on Tuesday Mr Rizzi believed the oboe player's standards had dropped to such a level he was "holding the entire orchestra back".
He said: "Because of the sensitivity of dealing with an artist, we felt it would be wholly inappropriate to give Mr Johnston a formal warning.
"That would put him under more pressure than the route we chose to take.
"We had a process of identifying what issues with his playing needed improvement, and communicating what steps were required to bring him back to acceptable standard.
"That process took three-and-a-half years."
The tribunal is expected to conclude on Friday.