Jose Mourinho endured frustration on his return to UEFA Champions League action with Chelsea as Basel came from a goal down to win 2-1.
Six years to the day after a 1-1 draw with Rosenborg that represented the final game of Mourinho's first spell in charge at Stamford Bridge, Chelsea were stunned by second-half goals from Mohamed Salah and Marco Streller.
Oscar fired the hosts ahead in the 45th minute in the Group E clash with his sixth goal in seven Champions League outings and the Brazilian also hit the bar prior to Salah’s classy left-footed leveller.
That goal prompted Chelsea to throw men forward, yet it was Basel - always dangerous on the break - who struck again when Streller beat Petr Cech with a near-post header from a corner.
Willian was handed his Chelsea debut and Marco van Ginkel a first start as Mourinho made five changes from the side beaten 1-0 by Everton at the weekend.
Basel recalled a host of players after fielding a weakened side for their Schweizer Pokal victory against Munsingen.
Mourinho's men unsurprisingly started the game on the front foot, albeit without creating any clear-cut opportunities.
There was a scare for Basel goalkeeper Yann Sommer in the 15th minute when he fumbled a corner from the left, but a free-kick was swiftly awarded in his favour.
The pacey Salah - a scorer at Stamford Bridge in last season's Europa League semi-final between the two sides - represented the main threat when Basel launched occasional attacks.
After Eden Hazard had spurned a rare clear sighting of goal for Chelsea following good work from Samuel Eto'o, Salah also proved wasteful when cutting in from the right and curling a shot over the bar.
Despite dominating possession and the corner count, the hosts remained frustrated as half-time approached.
However, Chelsea were lifted on the stroke of the interval as Oscar popped up with a timely goal.
David Luiz set the attack in motion by stepping into midfield and Oscar latched on to a delicate throughball from Frank Lampard to find the bottom-left corner with a first-time shot on the turn.
Streller was close to connecting with a left-wing cross early in the second half before Oscar struck the bar at the other end with a tremendous effort from just outside the area.
Hazard failed to hit the target once again either side of Branislav Ivanovic twice threatening from set-pieces.
Chelsea were then punished for not extending their lead when a cross from the left broke via Streller to Salah, who emulated Oscar by only requiring one touch to find the net.
Although Chelsea poured forward in search of a late winner, it was Basel who finished the stronger and their encouraging play gained reward as Streller shocked the home crowd.
|16||M. van Ginkel||42'|
|Coach: José Mourinho|
for Willian 67'
for F. Lampard 76'
for M. van Ginkel 76'
|Batshuayi worth the money, insists Cahill|
|Arnautovic signs new Stoke deal|
|Smith leaves Liverpool for Bournemouth|
|Barcelona insist Arda Turan will stay|
|Andre Gomes: Barcelona suit my identity better than Real Madrid|
|Niersbach to appeal FIFA ban|
|Barcelona agree Mascherano renewal|
|Fernandinho can play in 10 positions - Guardiola|
|Reading´s kit launch is out of this world|
|Ben Arfa: I do not want to be PSG´s star player|
|FA Cup to trial fourth substitute|
|We want Balotelli and he wants us, says Besiktas chief|
|Crowd welcomes Higuain as he arrives for Juventus medical|
|Guardiola warns Man City stars: If you´re not fit, danger is coming|
|Mkhitaryan prepares to prove himself at United|
|Cavani: No pressure replacing Ibrahimovic|
|Wenger vows to keep transfer plans ´secret´ after Lacazette snub|
|Brannagan open to Championship loan move|
|Wenger wants to sign Mertesacker replacement|
|Ancelotti: Bayern´s transfer business done|
|Brisbane Roar sign former Danish international Kristensen|
|Verratti, Luiz missing for PSG|
|Sounders part ways with foundation coach Schmid|
|Mane turned down Manchester United for Liverpool|
|Zidane on Pogba: Until August 31, anything can happen|
|Mkhitaryan driven by father´s death|
|Inter rejected Napoli offer for Icardi, says president|
|Clichy: City fighting fit after Guardiola pizza ban|
|Everton and Burnley win as Hull are held|
|Ajax held by PAOK after Cillessen howler|
|Conte left frustrated by ´crazy´ money in transfer market|
|Neymar makes Barcelona case to Gabriel Jesus|
|Rostov comeback twice for Champions League draw with Anderlecht.|
|Arsenal defender Mertesacker set for lengthy lay-off|
|Conte not selling ´fantastic´ Matic|
|Ibrahimovic keen on MLS and Beckham´s Miami project|
|Neymar: I play for Messi, he´s the man|
|Barcelona reveal details of Andre Gomes deal|
|Suarez bullish over Barcelona prospects|
|Ajax claim Napoli keen on Milik to replace Higuain|
|Totti labels Higuain´s Juventus move ´a disaster´|
|Juventus confirm Higuain deal|
|Pato to Villarreal ´in the final stage´|
|PSG sign Lo Celso|
|Muller: Beating Dortmund will be more fun this season|
|Juventus sign Higuain from Napoli for €90m|
|Pastore: I´m like God in Paris|
|Injured Lanzini out of Olympics|
|Allegri unperturbed by Higuain fee|
|Menezes replaces Bento at Cruzeiro|
|Sporting rejected major bids from Inter and Liverpool for Joao Mario, claims father|
|Pochettino pleased by Tottenham despite Juventus defeat|
|Eriksson: Allardyce the right man for England|
|Mourinho makes United train after stepping off plane from China|
|Hazard can still match Messi, says Pedro|
|Pjanic shows there is life at Juve, with or without Pogba|
|Juventus 2 Tottenham 1: Benatia bags win for Serie A champions|
|Dembele: I am not the Bundesliga´s next superstar|
|Lyon claim €35m Arsenal offer for Lacazette rejected|
|Donnarumma dreaming of Milan captaincy as he eyes long-term stay|
|Robson: Ibrahimovic can match Van Persie´s first year at United|
|Rooney should remain England captain - Eriksson|
|Emery wants new striker at PSG|
|Santos accept Juventus bid for Gabriel|
|Eriksson expects Sweden to try and tempt Ibrahimovic out of retirement|
|Spurs signing Janssen almost quit|
|Leicester stay best for Mahrez - Ranieri|
|Allardyce to take Mourinho cue on Rooney|
|Ings ready to outdo big-money signings|
|Henderson optimistic over Liverpool campaign|
|Allardyce hardened to the challenge of England post|
|Barcelona announce record revenues for 2015-16|
|Moyes enjoys Sunderland win as Palace beat Colchester|
|Stoke complete Allen signing|
|Roma coach Spalletti warns suitors off Manolas|
|Cresswell out for up to four months with knee injury|
|Burnley fan banned by club for racist abuse|
|Dad won´t let me play at the Olympics - Larsson Sr pulls rank|
|Kostic joins Hamburg on five-year deal|
|Tevez: I´d turn down Chelsea and Napoli to stay at Boca|
|Mayoral inspired by Benzema for Wolfsburg stint|
|Allardyce straight into competitive action with England|
|Liverpool, Sevilla fined for Europa League final incidents|
|Barcelona seal Guillemenot signing as part of new Servette deal|
|Niersbach handed one-year ban over World Cup corruption|
|Chelsea and Everton ´still interested´ as Koulibaly eyes Napoli exit|
|´Still working hard´ - Balotelli trains with Liverpool kids|
|Winter breaks, long-ball football and the World Cup: Allardyce in his own words|
|Inter warn Napoli Icardi is not for sale|
|Zanetti wants Simeone back at Inter|
|Stoke snap up Sobhi|
|PSG tougher under Emery - Lucas Moura|
|Totti not ready for retirement - Pallotta|
|Confident Allardyce reveals plan for England success|
|Pochettino to discard three Tottenham players|
|Allardyce: Rooney must wait for captaincy decision|
|Aubameyang: I will only leave Dortmund for Real Madrid|
|Allegri silences questions on Pogba|
|Bruce stands by decision to quit Hull City|
|Pochettino: Not the right time for Argentina job|
|Inter yet to approach De Boer with Mancini exit rumoured|
|Ancelotti trusts me more than Guardiola - Ribery|
|Wijnaldum rejected Everton for Klopp|
|Pre-season Manchester derby cancelled|
|Coutinho excited by ´fast´ Liverpool recruits|
|Cristiano Ronaldo and Conor McGregor step into the ring together|
|Mancini coy on reports linking Icardi to Napoli|
|Nolito reveals why he chose Man City over Barcelona|
|Inter 1 Paris Saint-Germain 3: Icardi absence in defeat fuels Napoli talk|