The AFC has today written to both his club and Football Federation Australia saying Vidmar is under-qualified to be the head coach in the prestige competition - despite Vidmar leading his side to the ACL final just two years ago

The AFC has has ruled he cannot be registered as the head coach as he does not fulfil the minimum coaching criteria for AFC Champions League.

In a letter sent to the Football Federation Australia (FFA), AFC said Vidmar would need to complete the FFA/AFC ‘A' Licence course (or any coaching equivalent to the AFC ‘A' Licence) before he can be registered as head coach for the club.

However, Vidmar can be registered as an Assistant Coach to participate in the AFC Champions League.

Adelaide United today appointed youth team coach Joe Mullen - who has the relevant coaching qualification - will be head coach for the club's Asian Champions League campaign.

"Joe Mullen is qualified as an AFC/FFA ‘A' level accredited coach, and has already completed Part 1 of the AFC's Pro Diploma coaching certificate and is due to complete Part 2 in August this year, " said Adelaide United CEO Sam Ciccarello.

"While Joe is qualified to have the title of Head Coach, Aurelio, who is in his third year coaching the club and took the club to the Final of the AFC Champions League in 2008, will continue his role as senior coach."

At the end of the 2007/08 season, Adelaide United proceeded almost immediately into the 2008 AFC Champions League and in effect, Vidmar has only had one off-season, in 2009, and in that short time he completed and passed the B Licence course.

Late in 2009, the FFA started a special Part 1 of the FFA/AFC ‘A' Licence course, specifically for Vidmar and the other Hyundai A-League coaches needing A Licence accreditation. Vidmar has attended and satisfied all requirements to this stage and by February 19, he will have completed the necessary requirements for Part 1 of the course.

"The time required off season to take these courses is typically 2-3 weeks in duration, and are conducted in Sydney or Canberra," Ciccarello said.

"Since we qualified for the 2010 AFC Champions League we have worked tirelessly with the FFA to seek ways for Aurelio to fully qualify and be able to coach in the ACL."

Vidmar is due to undertake Part 2 of the course after the completion of the 2010 AFC Champions League Group Stage.

"I'm happy to help the club out and add my input in any way I can and in any capacity, so to help in this tournament will be great," Mullen said on his appointment for the ACL.

An FFA spokesman today said: "Football Federation Australia and Adelaide United were aware of AFC regulations regarding coaching licences.

"FFA has worked consistently with all Hyundai A-League coaches to bring qualification levels up to AFC standards since joining the confederation in 2006.

"Vidmar's ineligibility due to AFC coaching licence requirements does not rule him out of a coaching role at Adelaide United for the AFC Champions League and he will continue developing his squad in an assistant coaching role until he can complete his FFA/AFC "A" Licence ."

The spokesman added: "Aurelio Vidmar was nominated for AFC Coach of the Year in 2009 and is widely acknowledged as one of the top coaches in Australia."

Meanwhile however, former Newcastle Jet Adam Griffiths has been cleared to be registered for Adelaide's ACL squad by the AFC, despite being ineligible to play in the A-League.

Adelaide are now awaiting an International Transfer Certificate from his current Saudi Arabian club, Al-Shabab to allow him to complete his move to the South Australian side.