It was another crushing night for Walter Mazzarri's Inter as they were outplayed by rivals Juventus in Turin.
The Nerazzurri have been a long way off the Old Lady's pace this term and went into the game as underdogs.
Goals from Stephan Lichtsteiner, Giorgio Chiellini and Arturo Vidal put the game beyond doubt before Inter grabbed a consolation from Rolando.
Inter are now winless in five while Juventus' lead at the top of Serie A is extended to nine points after Roma's game with Parma was rained off.
Juventus were dominant all over the pitch, but coach Mazzarri was especially disappointed with the performance of Croatian midfielder Kovacic who was given the tough task of dealing with Andrea Pirlo, who ran the match.
"I thought Kovacic was in the ideal position to play well," Mazzarri said to Sky Sport Italia after the game.
"He was always going to get more space in deeper positions and we know he has quality.
"But after Ruben Botta came in, Pirlo wasn’t quite so free. There was meant to be someone on him, and that was Kovacic, but that person didn’t do enough, so he’d get stuck in-between and leave us a man down in midfield."
Manchester United had been linked with a move for Kovacic in the January transfer window but may now be relieved that they didn't table a bid.
The pressure is mounting on Mazzarri and he admitted that his men aren't at the same level as Juventus but doesn't believe all is lost.
"We need to learn from our mistakes and grow a lot," he admitted. "The ability is there and the tactics are right.
"It's a year of growth and evaluation and we just need a win to turn things around."
image: © batrax