Mourinho achieved great success in two separate spells with the Blues winning the Premier League title on three occasions alongside three League Cup triumphs and an FA Cup.
The Portuguese failed to claim the league crown in his single season at Old Trafford to date but has United joint top this term after a much improved start to their campaign.
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And Mourinho believes it is his newly calm demeanour that is making the difference.
“I'm a better coach today than I was before because I can control my emotions,” he told Record . “These days I face difficulties with more maturity – it means I keep my feet on the ground.”
United sit alongside rivals City at the top of the table but Mourinho is already keen to dampen talk that the title heading to Manchester is a foregone conclusion.
“Things started off more difficult last year and the season turned out really well,” he added after United sealed an EFL and FA Cup double last term. “But this year has started off really well so we don't know how it's going to end.
“In another league [our start] would mean we've basically won the title, but in England in means nothing.”