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.
Chelsea scored the fewest goals of the top six last season and have also struggled in that department in pre-season.
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.
"The first half was hard. I'm really happy to be here and looking forward to joining them".
And in the first game of the season it brought some reward with the French World Cup victor scoring the opener against Huddersfield.
France World Cup victor N'Golo Kante volleyed in the opener in the 34th minute, Jorginho netted a penalty on his Premier League debut before halftime and Pedro drove home the third with an angled drive after the break.
August 11 Partial Solar Eclipse: Best Times, Places to See
People in northern China will on Saturday afternoon get to experience the only solar eclipse visible to the country this year. The August eclipse began over the cold North Atlantic and Greenland before moving in a northeast direction.
The Blues' new star in the midfield is Jorginho, who came over to Chelsea with Sarri from Napoli.
Huddersfield felt hard done by because they believed that Christopher Schindler's boot-to-boot contact with Marcos Alonso was accidental.
FW Pedro, 8 - Linked up well with Azpilicueta in forward passages of play and was the main beneficiary when Hazard came on as he latched onto a pass from the Belgian worldwide to smartly score the final goal.
As it was, David Wagner's team were unable to do enough to cause serious problems for Kepa on the young Basque 'keeper's debut. However, this was forgiven just before half-time when he made a buccaneering break into the Huddersfield box and drew a foul to secure the penalty which Jorginho converted.
9 - With the exception of handing Kepa Arrizabalaga a debut in goal, Sarri played it safe with his first league line-up by opting for experienced heads to do his high-press bidding.
Huddersfield, meanwhile, have another tough matchup ahead and will play Manchester City away next weekend. Could they be potential title challengers this season?