Chelsea made hard work of it, but did enough to see off Servette and move into the league phase of the Europa Conference League.
After a 2-0 home win in the first leg, Christopher Nkunku's early penalty looked to have sealed the qualification play-off, only for the Swiss side to score twice to set up a nervy finish, with them missing a late chance that would have taken the tie to extra-time.
With Enzo Maresca only having one more day to trim his already bloated squad, with Raheem Sterling and Ben Chilwell among the players that could leave on Friday's transfer deadline day, qualification in Switzerland was important.