Graham Potter opted for Cesar Azpilicueta ahead of recent arrivals Kalidou Koulibaly and Wesley Fofana as Chelsea switched to 4-3-3 in their new head coach's first game.
The Blues operated in a 3-4-3 system for most of Thomas Tuchel's tenure, but the German was dismissed after an underwhelming start to the season.
Potter was convinced to leave Brighton and Hove Albion for Stamford Bridge and made three changes ahead of his first game at home to Salzburg in the Champions League on Wednesday.
Thiago Silva returned to the starting line-up, with club captain Azpilicueta partnering the centre-back as Potter decided to leave out Koulibaly and Fofana, who were recruited from Napoli and Leicester City respectively.
Jorginho came in to the midfield trio, along with Mateo Kovacic and Mason Mount, while former Brighton defender Marc Cucurella replaced Ben Chilwell at left-back.
Chelsea continued with the same front three, though – Raheem Sterling, Kai Havertz and Pierre-Emerick Aubameyang up top, the latter making his home debut for the Blues.
The Blues lost 1-0 at Dinamo Zagreb in their Group E opener, which was Tuchel's 100th game in charge, and also his last.