Coutinho played for the Argentine at Espanyol.
"The last time I spoke to Pochettino was just before I joined Liverpool (when he tried to sign him). I know from my time working with him he is a very impressive person," Coutinho told the Telegraph.
"It is no surprise to me at all to see Southampton have started the season so well. He is extremely dedicated to training, making his players work very hard. If there is something not correct in training, he will push to make it 100 per cent correct."
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