According to the club's official website, Arrizabalaga will wear the number one jersey at Stamford Bridge whilst Kovacic will sport the number 17 in his year in West London.
Kepa Arrizabalaga replaced Thibaut Courtois for a world-record fee for a goalkeeper in a chaotic finish to the transfer window this week, while doubts over the futures of Eden Hazard and Willian have dogged Chelsea's pre-season preparations.
With the arrival of Jorginho, Maurizio Sarri and Sarrismo, N'Golo Kante will find himself in a slightly more advanced position at Chelsea this season.
There were questions over whether Huddersfield could keep things rolling after their achievement last season and they really didn't play badly, especially in the first half.
"I have references about him from players like Pepe Reina, who was at Napoli and knows him, and was very happy with him".
Hazard - who is stalling on signing a new £300,000 a week deal - is not openly pushing to leave and has spoken to boss Sarri since returning from his break after the World Cup.
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Huddersfield felt hard done by because they believed that Christopher Schindler's boot-to-boot contact with Marcos Alonso was accidental.
"Hazard has congratulated me on signing for Real Madrid", said Belgian goalkeeper.
Jorginho converted the penalty, a skip on his run-up leaving Hamer on his backside.
Sarri claimed that he couldn't simply replicate the attractive style for which he became famous at Empoli and Napoli but indicated that the next weeks would be critical. Hazard drives forward, slipping through Pedro at the flawless moment.
Kepa did not make a save of note on his debut.
Alex Pritchard was a risky creative force in the final third, Steve Mounié came close on three occasions and hit the post with a close-range header just minutes after Kanté opened the scoring.
Next up for Huddersfield is a daunting trip to take on champions Manchester City at the Etihad a week on Sunday, a match you can see live on Sky Sports Premier League.