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'
|MLS Review: Keane shines at Gerrard´s Galaxy unveiling|
|Counter-attacking the key for Japan|
|Jimenez happy at Atletico|
|Gerrard predicts ´successful future´ with Galaxy|
|Iniesta can´t see Real selling Ramos|
|Keshi sacked as Nigeria coach|
|Three finals, three defeats for Messi, Mascherano|
|Nani close to Fenerbahce move|
|Sampaoli revels in ´unbelievable joy´|
|Bravo: Copa victory a dream|
|Martino: Argentina should have won|
|Chile 0 Argentina 0 (4-1 on penalties): Hosts end trophy drought|
|Germany 0 England 1 (after extra time): England make World Cup history|
|Kenya 0 Ethiopia 0 (agg 0-2): Hosts sent out of CHAN qualifiers after second penalty miss|
|Dortmund put 17 past Olympians, Bremen hand out thrashing|
|Dinamo Zagreb confirm arrests of coach and club president|
|I didn´t know who Wimbledon guest Klopp was - Brown|
|LeBron James backs Liverpool captain Henderson for FIFA 16 cover.|
|Ramos: I am not negotiating with anyone|
|Valencia complete Mina swoop|
|United States v Japan: US seek final redemption|
|Hanousek consigns Celtic to defeat|
|Roma confirm Dzeko interest|
|Arsenal forward Podolski completes Galatasaray switch|
|Warm Dortmund welcome delights Tuchel|
|Silva vows to fight for Madrid place|
|Mancini hints at Shaqiri and Santon departures|
|Bojan raring to go after return from injury|
|Babel backs Firmino to shine at Liverpool|
|Falcao must wait to impress, warns Chelsea favourite|
|Bartomeu: Deal in place for Turan|
|Parejo re-signs with Valencia|
|MLS Review: Sounders return to winning ways|
|Klinsmann unhappy with USA performance|
|High hopes for Paraguay - Diaz|
|Gareca: More to come from Peru|
|Gerrard had European offers|
|Argentina out to spoil Chile´s party - Martino|
|Sampaoli: Chile won´t change style|
|Di Maria will come good at United - Rojo|
|Peru 2 Paraguay 0: Gareca´s men finish third at Copa|
|United States 4 Guatemala 0: Klinsmann´s men win comfortably|
|´I’d prefer no-one to know my name´ - Bassett|
|Matthews completes Sunderland move|
|Podolski set for Galatasaray medical|
|Gundogan inspires Dortmund victory|
|Inter confirm Montoya capture|
|Murillo joins Inter, as Kuzmanovic and Obi depart|
|Falcao signing not a risk, says former Chelsea star|
|Deeney agrees new Watford deal|
|Confidence and service the key to Falcao success at Chelsea|
|No bids for ´Chelsea target´ Baba, claim Augsburg|
|Derby swoop for Ince|
|Fiorentina consider legal action over Salah ´no-show´|
|Chelsea the team to beat in the Premier League, says Neville|
|Storari exits Juve for Cagliari|
|UEFA removes FFP restrictions on Man City and PSG|
|West Brom hope for new owners within the month|
|Chelsea agree loan deal for Falcao|
|Kuyt eyes trophies on Feyenoord return|
|Chile v Argentina: History beckons ahead of Copa America final|
|Wallace extends Monaco loan|
|Mihajlovic wants to instill fear factor at Milan|
|Mignolet improving at Liverpool - Grobbelaar|
|Mumbai City name Anelka player-manager|
|Olivia the parrot predicts Japan to win Women´s World Cup|
|Lusitans coach blasts Bilic´s ´lack of respect´|
|Sakho eyes more Europa League wins|
|Gareca wants Peru to keep building|
|Chile ´no chance´ if Argentina produce their best - Diaz|
|Ocampos joins Marseille permanently|
|Europa League Review: Cloud-nine Brondby ignite opening round|