There has been some criticism of the Portuguese, saying the game has left him behind.
On TalkSport, O'Hara says Mourinho remains one of the best managers in the world and pointed at the way he has dealt with Tottenham's injury crisis as evidence.
He said of those who feel Mourinho is out of touch: "It's disrespectful. It's a little bit out of order. It's a bad shout. To say he's yesterday's man is complete nonsense. They just beat Man City, with a tactical way of playing. Spurs have got their two best players out.
"He's had to adapt. I don't agree that he's yesterday's man. He gets a lot of stick from the press. The guy is one of the greatest managers ever to be in the Premier League. Since Mourinho's come in, they've gone up in terms of form. He's doing it with a squad that's really struggling. You can't say he's yesterday's man."
Mourinho will always divide opinion - polarising those who believe he's a born winner who demands far more respect or those who want to write him off.
As ever, the truth is somewhere in between. Is there any need for him to be so negative at times? Not really, and the way Tottenham played on Tuesday has to reflect badly on him to some extent.
At the same time, he has taken Tottenham forwards from where they were under Mauricio Pochettino this season and is now close to getting the club into the top four.
He still has something to offer, especially in a Premier League season where rivals have struggled for consistency, but he is probably past his peak also.
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