Middlesbrough boss Aitor Karanka believes Jose Mourinho is a better manager than Pep Guardiola.
Mourinho and Guardiola took over Manchester United and Manchester City respectively in the summer, with the duo having experienced mixed fortunes since then.
Mourinho's United have picked up just two wins from their last seven matches in all competitions and sit eighth in the Premier League, while Guardiola's City are eight points ahead of their local rivals at the top of the table and have just seen off Barcelona 3-1 in the Champions League.
But Karanka, who was Mourinho's assistant at Real Madrid, told reporters: "For me, yes Jose is better than Pep. I have been working with him [Mourinho] for three years and I know his methodology, I know his character, I know everything. For me, it has been amazing to work with him, so I know him better than Pep."
Karanka added that, despite also hailing from Spain, he has never been close with former Barcelona boss Guardiola.
"We are not really friends because Real Madrid versus Barcelona were such big games and I wasn't with him in the national team so I didn't have a relationship with him," Karanka said.
"He is one of the best coaches, but I don't think one is much, much better than the rest because we have Jose, we have Pep, but we also have Diego Simeone in Spain, Jurgen Klopp here, Mauricio Pochettino, Antonio Conte with Chelsea and Massimiliano Allegri in Italy."