Despite finishing in sixth position in the Premier League during 2023-24, the Blues have only qualified for the Europa Conference League playoffs courtesy of Manchester United upsetting neighbours Manchester City in the FA Cup final.
As a result, Enzo Maresca and his squad have been presented with a two-legged tie against Servette, the victors going through to compete in the new 36-team league phase in this tournament.
Having only lost 2-1 on aggregate to Portuguese outfit Braga and currently sitting in fifth place in the Swiss Super League, Servette have shown that they will be no pushovers.
However, as Sports Mole will explain, Chelsea are no strangers to being upset by teams from Switzerland.
St Gallen (2000-01 UEFA Cup first round)
Claudio Ranieri announced himself to English football in September 2000 by earning a 3-3 draw at Manchester United in the Premier League, helping win over Chelsea fans in the process.
However, five days later, the West Londoners were being dumped out of the UEFA Cup at the first-round stage by little-known St Gallen, a club that had previously won just one main-stage European tie in their history.
Chelsea had been leading 1-0 from the first leg with Christian Panucci scoring the only goal of the game at Stamford Bridge, but Ranieri's side were behind in the tie come half time of the reverse fixture.
Sascha Muller and Charles Amoah netted the goals that secured one of the greatest results in their history on what was, in sharp contrast, a nightmare night for Chelsea and club legend Roberto Di Matteo.
The Italian midfielder sustained a triple leg fracture that would ultimately end his playing career, the then-31-year-old accepting defeat in his recovery and deciding to retire 18 months on from the incident.
Basel (2012-13 Europa League semi-finals)
David Luiz is not short of famous moments from a 248-game Chelsea career compiled across two stints, yet his most pivotal perhaps came within a week of each other at the back end of 2012-13.
Chelsea - European champions at the time - were heavily backed to overcome Basel in the Europa League semi-finals, only for a Mohamed Salah penalty to pull the Swiss side level at the back end of their home first leg.
However, up stepped Luiz in the 94th minute to drill a low free kick into the far corner of the net, securing Chelsea a precious 2-1 advantage ahead of the reverse fixture at Stamford Bridge.
Basel, through Salah again, were back level in the tie come half time in West London, only for a nine-minute three-goal burst from Chelsea after the break putting them into an unassailable lead.
The third of those was an incredible strike from Luiz. Teed up around 25 yards out, the charismatic Brazilian curled a magical strike into the far top corner, leaving the goalkeeper unmoved, and it set up a final against his former club Benfica which Chelsea ultimately won by a 2-1 scoreline courtesy of Branislav Ivanovic's last-gasp header.
Basel (2013-14 Champions League group stage)
Chelsea and Basel would renew acquaintances in the Champions League the following campaign, the English outfit believing that they had been provided with a routine group that also included Schalke 04 and Steaua Bucuresti.
Although Chelsea, who had Jose Mourinho back in charge, would ultimately qualify in top spot, they lost both games to their increasingly-familiar foes.
Despite a goal from Oscar putting them ahead at Stamford Bridge on matchday one, Salah and Marco Streller netted in the final 19 minutes to earn Basel a famous win.
Mourinho's team responded with three wins, three clean sheets and 10 goals before the reverse clash at St Jakob Park, seemingly on course for a fourth shutout until Salah incredibly netted for the fourth game in succession against Chelsea three minutes from time.
A 1-0 triumph over Steaua on matchday six was required to finish in first place, Chelsea eventually reaching the semi-finals before losing to Atletico Madrid.
Meanwhile, Salah's contributions throughout 2013 impressed Mourinho to the extent where he signed the Egypt international in January. Salah would famously score just twice in 19 appearances for the Blues before going on to put together one of the greatest Liverpool careers in their illustrious history.
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