The Croatian has started all five Premier League matches since Tuchel took charge at Stamford Bridge.
"I love him. I could wake the guy at 3 at night and he will be at Cobham at 3.15 ready to give everything," Tuchel told the 5th Stand.
"I need to calm the guy down in training, that he's not doing too much. It's a pleasure to have him."
Kovacic completed 90 minutes in the league four times under Lampard earlier in the season, and he has already matched that total under Tuchel.
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