Aitor Karanka has backed Alvaro Morata to be a success at Manchester United amid suggestions that the Real Madrid striker is set to become Jose Mourinho's second signing of the summer. The former Middlesbrough manager says that the Spaniard "has everything" to be a "spectacular player for the Premier League".

Karanka spent three seasons working as Mourinho's assistant at Real Madrid from 2010 to 2013, before taking over at Middlesbrough, and was at the Santiago Bernabeu in December 2010 when Mourinho handed Morata his first-team debut during a 3-1 victory over Zaragoza.

Indeed, the former Middlesbrough manager had learnt about Morata's talent as striker long before whilst working with the Spanish national youth teams from 2008 to 2010.

Thus, he is confident that Morata's expected reunion with his good friend Mourinho at Old Trafford will be a success.

"Alvaro fits anywhere," Karanka said to Cadena Ser when asked what to expect from the current Real Madrid striker at Manchester United. "Since he was with us at the age of 19 (we could see it). I know him since he was 17 because he came to the Under 17 World Cup in Nigeria (in 2009). Alvaro is the classic player that can fit anywhere. He has everything. The year he spent at Juventus was good for him to mature. For this football (the Premier League) he is a spectacular player."

Karanka may well have some insights into the progress of negotiations between Real Madrid and Manchester United, revealing during the interview he is still in "weekly" contact with his friend Mourinho.

Cadena Ser insists that it is only a matter time before Morata becomes Mourinho's second signing of the summer - following the arrival of Victor Lindelof from Benfica.

Earlier this week, El Larguero reported that the deal with the player is already done and that the agreement between Real Madrid and United could be between €70m (£61.5m, $78.3m) and €80m.

Meanwhile, another proposed move that looks increasingly unlikely is the one that which have seen David De Gea leaving Manchester United to join Real Madrid.

Recent reports in Spain have claimed that Los Blancos interest in the keeper had gone cold after Zinedine Zidane asked club president Florentino Perez to stick with Keylor Navas.

"This is football but he is not bad in Manchester," Karanka said when asked about De Gea. "Here [in England] he is very respected, he is comfortable here and he is not bad at Manchester either."

Karanka, meanwhile, revealed that he has turned down some interesting proposals to return to La Liga because he wants to continue his managerial career in England – after leaving Middlesbrough on March.