Porto collected ?13.3 million in compensation when Villas-Boas agreed to join Chelsea after claiming the Europa League, Portuguese League and Cup in his first year in charge.
Casting a shadow: Villas-Boas (right) was afraid of comparisons with Mourinho (left), says Da Costa
But Da Costa says Villas-Boas feared he could not emulate the success of Jose Mourinho, who also claimed a domestic and European treble in his first season before winning the league and Champions League a year later.
Da Costa said: 'Villas-Boas was living with Mourinho's ghost. He was afraid he would not have the same success as inhis first season. I think that was the crucial aspect in his departure.
Not impressed: Porto president Da Costa
'If I was his father I would have told him what I told him as his president and his friend: that he should have stayed at FC Porto.
'In football, when you talk about European giants, the measure is not Chelsea. It's Real Madrid, Barcelona or Manchester United. I told him that this would be (Pep) Guardiola's last season at Barcelona and that was the ideal club for him, but he was scared of the comparisons with Mourinho and left.'
Chelsea are interested in signing Porto striker Falcao and midfielderJoao Moutinho and Da Costa admitted only forward Hulk is definitely notfor sale.
He added: 'If 10 players leave I have replacements for each one of them. There is only one who I don't have a replacement for, who is Hulk.If a player such as Alvaro Pereira or Falcao left, FC Porto would continue to play in the same style. But as there is no player with the same characteristics as Hulk, our game would have to change.'
Reports in Portugal claim it is unlikely Moutinho willjoin the Blues this summer because of his ?35million release clause.
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Source: Daily Mail
Source: Daily Mail