FC Basel produced the first big upset of this season’s Champions League when they came from behind to beat Chelsea at Stamford Bridge.

A stunning Lorenzo Insigne free-kick proved decisive for Napoli who beat 10-man Borussia Dortmund 2-1 while Lionel Messi bagged a hat-trick as Barcelona crushed Ajax 4-0 at the Nou Camp.

Jose Mourinho’s dreams of winning the Champions League with Chelsea suffered an early setback yesterday when the Londoners fell to a shock 2-1 home defeat by Swiss champions Basel in their opening Group E match.

Chelsea looked short of ideas all night in a stuttering display, though they led 1-0 following a neat finish by Oscar just before half-time.

The Brazilian hit the bar soon after the restart as Chelsea briefly turned on the style but they were never able to take complete control and Mohamed Salah equalised in the 71st minute.

Basel, beaten by Chelsea in the Europa League semi-finals last season, grew in confidence and scored again 10 minutes later when captain and centre forward Marco Streller cleverly glanced in a near-post header from a corner.

“I’m not in shock,” Mourinho told Sky Sports after Chelsea’s first home defeat in the Champions League group stage in 30 matches. “Sometimes you win sometimes you lose.

“I’m not happy of course. We have taken a step back in qualification but we have to assume responsibility. We have five games left to finish in the top two.

“Basel played very well. We had a lot of the ball but we couldn’t create many chances. Emotionally this is not a mature team and when you are in a difficult position it was not enough.”

At the San Paolo stadium, Gonzalo Higuain’s 29th minute glancing header and Insigne’s superb strike in the 67th minute looked to have given the Serie A leaders a fully deserved win against last season’s beaten finalists Borussia Dortmund who had goalkeeper Roman Weiden-feller sent off late in the first half.

However, the Italians missed a series of chances in the second half, and a Juan Zuniga own goal in the 87th minute left them sweating against dogged Dort-mund.

Weidenfeller was given a straight red card after he rushed out of his area to beat Higuain to Insigne’s floated pass in first half stoppage time and blatantly batted it away with his hand.

The Bundesliga leaders also had to play most of the match without manager Jurgen Klopp on the touchline after he was sent to the stands after remonstrating with the fourth official about Neven Subotic not being allowed back onto the pitch in the lead up to the opening goal.

Arsenal recovered from an unimpressive first half to defeat Marseille 2-1 in France to move level with Napoli at the top of Group F.

Theo Walcott volleyed home in the 65th minute after benefiting from Jeremy Morel’s defensive blunder before Aaron Ramsey put the result beyond doubt seven minutes from time with a deflected low shot.

Olympique Marseille had a handful of chances with Andre-Pierre Gignac, Andre Ayew and Rod Fanni coming close to scoring before Jordan Ayew reduced the arrears with a penalty in added time.

Messi treble

Argentine World Player of the Year Messi lit up the Nou Camp with a brilliant curling free-kick in the 22nd minute, a trademark dash in from the right and clinical finish 10 minutes into the second half and a low shot into the corner from the edge of the area 15 minutes from time.

He is the first player to score four trebles in Europe’s elite club competition and took his overall goals tally to 62 in 80 appearances, nine short of record scorer Raul of Real Madrid.

Defender Gerard Pique had netted Barcelona’s third with a header from Neymar’s centre in the 69th minute and goalkeeper Victor Valdes continued his fine run of form by saving Kolbeinn Sig-thorsson’s 77th-minute penalty.

In the other Group H match, scrappy Milan, barely able to string two passes together, still managed to score twice in the last nine minutes to snatch a fortuitous 2-0 win over Celtic at San Siro.

Celtic looked the more likely side to win until Colombia defender Cristian Zapata’s low shot, which was going wide, was deflected into the goal by Emilio Izguirre.

Sulley Muntari added the second, snapping up a rebound after Mario Balotelli’s free-kick was parried by goalkeeper Fraser Forster.

Summaries

Schalke 3
Uchida 67; Boateng 78; Draxler 82;
S. Bucharest 0

Chelsea 1
Oscar 45;
Basel 2
Salah 71; Streller 81;

Marseille 1
Ayew 90 pen;
Arsenal 2
Walcott 65; Ramsey 83;

Napoli 2
Higuain 29; Insigne 67;
B. Dortmund 1
Zuniga 87 og;

Red card: Weidenfeller (BD) 45.

A. Vienna 0
Porto 1
Gonzalez 55;

A. Madrid 3
Miranda 39; Turan 64; Baptistao 80;
Zenit SP 1
Hulk 58;

Milan 2
Zapata 81; Muntari 86;
Celtic 0

Barcelona 4
Messi 22, 55, 75; Pique 69;
Ajax 0

Missed penalty: Sigthorsson (A) 77.

Group E

Schalke vs S. Bucharest - 3-0
Chelsea vs Basel - 1-2
01/10/13: Basel vs Schalke
01/10/13: S. Bucharest vs Chelsea
22/10/13: S. Bucharest vs Basel
22/10/13: Schalke vs Chelsea
06/11/13: Basel vs S. Bucharest
06/11/13: Chelsea vs Schalke
26/11/13: Basel vs Chelsea
26/11/13: S. Bucharest vs Schalke
11/12/13: Schalke vs Basel
11/12/13: Chelsea vs S. Bucharest

Group F

Marseille vs Arsenal - 1-2
Napoli vs B. Dortmund - 2-1
01/10/13: B. Dortmund vs Marseille
01/10/13: Arsenal vs Napoli
22/10/13: Arsenal vs B. Dortmund
22/10/13: Marseille vs Napoli
06/11/13: B. Dortmund vs Arsenal
06/11/13: Napoli vs Marseille
26/11/13: Arsenal vs Marseille
26/11/13: B. Dortmund vs Napoli
11/12/13: Marseille vs B. Dortmund
11/12/13: Napoli vs Arsenal

Group G

A. Vienna vs Porto - 0-1
A. Madrid vs Zenit SP - 3-1
01/10/13: Zenit SP vs A. Vienna
01/10/13: Porto vs A. Madrid
22/10/13: Porto vs Zenit SP
22/10/13: A. Vienna vs A. Madrid
06/11/13: Zenit SP vs Porto
06/11/13: A. Madrid vs A. Vienna
26/11/13: Porto vs A. Vienna
26/11/13: Zenit SP vs A. Madrid
11/12/13: A. Vienna vs Zenit SP
11/12/13: A. Madrid vs Porto

Group H

Milan vs Celtic - 2-0
Barcelona vs Ajax - 4-0
01/10/13: Ajax vs Milan
01/10/13: Celtic vs Barcelona
22/10/13: Celtic vs Ajax
22/10/13: Milan vs Barcelona
06/11/13: Ajax vs Celtic
06/11/13: Barcelona vs Milan
26/11/13: Celtic vs Milan
26/11/13: Ajax vs Barcelona
11/12/13: Milan vs Ajax
11/12/13: Barcelona vs Celtic