Chelsea qualified for the Champions League knock-out stages despite a limp performance as they were beaten by Basle for a second time in Group E.
Mohamed Salah's fine goal three minutes from time earned Basle a deserved 1-0 victory at St Jakob Park and completed a double over Jose Mourinho's Chelsea, who had travelled to Switzerland needing just a point to advance and a win to claim top spot in the pool.
However, Schalke's 0-0 draw at Steaua Bucharest means the Blues advance to the last 16 ahead of the December 11 meeting at home to the Romanians.
The Blues, who have nine matches next month, last season suffered the ignominy of becoming the first winners to exit the tournament at the group stage in defence of their title, before responding by beating Basle in the semi-finals en route to winning the Europa League.
This season, in the premier tournament, Basle have exacted a semblance of revenge.
Murat Yakin's side were out to prove their win at Stamford Bridge was not a one-off as the Swiss sought a place in the knock-out stages, or at least the Europa League.
Mourinho promised a different Chelsea to the one which lost in the opening group game, but saw his side outplayed.
The visitors survived calls for a penalty when the ball hit Frank Lampard on the arm after 17 minutes and Petr Cech made a series of saves to keep the Blues level, the best repelling a deflected Salah shot when the goalkeeper had already started his dive.
Fernando Torres, fit again after missing three games with an adductor injury, replaced Samuel Eto'o after 42 minutes when the Cameroon striker was taken off on a stretcher after falling awkwardly, and Eden Hazard followed him into the fray 10 minutes into the second half.
But neither could improve Chelsea's fortunes and Salah's strike settled matters in Basle's favour and left Mourinho and his men frustrated, beaten and with work to do.