The Blues made something of a slow start to the game as they struggled to click into gear in front of their home fans at Stamford Bridge.
However, Marcos Alonso scored the winner in the 73rd minute when he fired home an angled shot to hand Chelsea FC their third win in a row in the Premier League.
The 25-year-old Kovacic came on at the end of the first half to replace the injured Ross Barkley, and Lampard was full of praise for the Croatian’s performance.
Speaking at his post-match news conference at Stamford Bridge, Lampard said: “I saw a spirit and energy of the team – keep picking up the wins and take nothing for granted.
“We had a problem in the game, but solved it. Kovacic was outstanding and Christian [Pulisic] got at people. I am pleased, we have to play like that. We got our way.”
The Chelsea FC boss also singled out American playmaker Christian Pulisic for special praise after he replaced Mason Mount in the 64th minute at Stamford Bridge.
Lampard added: “I am really pleased for him. He is a hot topic [but] everyone has got a little carried away. To see him play that way [was encouraging].”
The win lifted Chelsea FC up into third place in the Premier League table ahead of Manchester City’s clash with Crystal Palace later on Saturday night.
Next up for the Blues is a trip to Amsterdam to take on Ajax in the Champions League, before a trip to Burnley in the Premier League next weekend.
The Blues have taken 17 points from their opening nine games in the Premier League under Lampard so far this season.
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