The former Barcelona captain Xavi admits he initially thought Louis van Gaal was an “idiot” but changed his mind after a week working with him.

The former Spain international was a youngster breaking through at the Nou Camp when Van Gaal was in charge at Barça and his first impression was not favourable.

However, he soon altered his view though he admitted the 64-year-old, now at Manchester United, was “poorly valued in the media”.

“After two days of training under him I thought, ‘Who is this idiot?’ After a week, I thought, ‘He’s right.’ He’ll always be in my heart, Louis van Gaal,” Xavi, now playing for the Qatari club Al Sadd, told espnfc.com.

“[He is a] good person, very good trainer. He has a very strong character but he’s calm in the Premier League because there’s less pressure.

“He’s much calmer than when he was at Barça or Bayern Munich. He’s honest, methodical and a real perfectionist. He’s very demanding, he’s strict and he wants to achieve the highest levels possible. He’s a tough fighter, yet he put trust into me when I was 17 and 18 years old.”

Xavi also has experience of being coached by José Mourinho, who worked for Van Gaal at Barcelona, and he has nothing but praise for the Portuguese, whose methods are under growing scrutiny at Chelsea.

“He was excellent in his three years at Barça,” Xavi added. “They said he was a translator. Rubbish. He was the assistant coach, someone who understood the philosophy of Barça and who shared many of the same characteristics of Van Gaal.

“He was very respected by the players. He trained us sometimes alone at Barça B and he was excellent. I’m surprised that he became known for another type of football, more defensive, because he wasn’t like that with us.”