G4 defeat strikes wrong chord.
Paul Wade taught Matt, 24, at Huddersfield University and said the only reason the band missed out was because Steve was the housewives' favourite.
"It was a complete injustice and a sad indictment of the British public's music taste," he blasted.
Opera boy band G4 were pipped at the post in the X-Factor final on ITV1 on Saturday night.
Huddersfield University graduate Matt and his band missed out on the pounds 1m recording contract to 35-year-old former pub singer Steve.
It was looking good for G4 after stunning performances of Nessun Dorma and indie-rock classic Creep by Radiohead.
But Steve managed to bag the majority of the more than 8m votes cast even after a blazing personal attack from judge Sharon Osbourne who called him "a fake".
Mr Wade, 60, is convinced G4 - whose other members are Jon Ansell, Michael Christie and Ben Thapa - would be stars.
"They have got off their backsides and done something different and that is so admirable," he said.
"It is very sad they did not win and I am still not sure quite why or how that happened but I think they will be stars.
"Matt was always a great pupil and I am very proud of what he has already achieved.
"For them it has not just been about turning up and singing they have had to spend a long time sorting out arrangements and harmonies - it was very impressive."
Matt, a bass singer, left Huddersfield University after gaining a master's degree and then studied at the Guildhall School of Music, in London, where he met the rest of the band.
Now the band are preparing for the X-Factor tour.
The 10-date arena tour in February includes all nine X-factor finalists. The finalists will perform at Manchester Arena on February 16 and Sheffield Hallam FM Arena on February 19.
* X FACTOR was trounced by the BBC's Strictly Come Dancing. 11.2m viewers tuned in to see East- Enders star Jill Halfpenny dance to victory. The X Factor peaked at 9.9m.