The Spurs boss hailed the victory as a "great European night" but warned his players that there is still work to be done in next week's away leg.
"It was a full 90-minute performance with excellent attacking football, reducing their chances and it was a great European night. We are not through yet and the San Siro is a difficult place to go," BBC Sport quotes him as saying.
"Gareth Bale is missing but we have the talent in the squad to cope with it."
Bale, Gylfi Sigurdsson and Jan Vertonghen were on target for the Premier League outfit, giving them a three-goal cushion to take into the second leg on March 14.