The Blues spent just one season working under Sarri, before Stamford Bridge legend Lampard took over, who has received plenty of plaudits for his man-management skills.
Kovacic is among those to have talked up a man who took plenty of important coaching lessons from Jose Mourinho, with Chelsea finding another manager capable of delivering both fun and success.
Kovacic told FourFourTwo: “I came to Chelsea under Sarri, but I must say that Lampard is an exceptional manager.
“He has kept the character he had as a player in his personality as a coach, which has inspired all of us.
“He commits himself with everything he’s got. Training is always challenging and different from last season.
“That’s probably the main difference between Lampard and Sarri, who made the concept of training quite monotonous.
“There were a lot of similar training sessions with a focus on tactical preparation.
“[Zinedine] Zidane was similar to the way Frank Lampard is a coaching, and their approaches really suit.”
Kovacic added: “I have to admit that I’m really enjoying it so far.
“I play with the ball a lot more and have greater freedom of movement – that’s why I think I’ve put in some great performances this season.
“Last year I was tied to a specific area, which became a bit predictable for our opponents and therefore made it harder for me.
“Sarri didn’t want long balls from defence when we were under pressure, which led us into some tough situations.
“Lampard, on the other hand, gives us more freedom to assess situations. It’s proved to be a good tactic, as it gives us unpredictability. We’ve scored lots of different goals this season.”
Lampard has guided Chelsea into fourth spot in the Premier League table, while also overseeing runs through to the last 16 of the Champions League and fifth round of the FA Cup.