Shakhter Karagandy's dream run in the UEFA Champions League looks set to continue after they stunned Celtic 2-0 on Tuesday.
The Kazakhstan outfit have already beaten BATE Borisov and Skenderbeu Korce to reach the play-off round, and put one foot in the group stages after their success over the 1966-67 European Cup winners at the Astana Arena.
The Scottish champions were guilty of some poor defending and wasting chances and will have a huge task to overturn the deficit in the second leg.
Andrey Finonchenko grabbed the opening goal when he pounced on a loose ball from a long throw in and Sergei Khizhnichenko doubled the advantage in the second half with a close-range header.
Kris Commons came closest for Celtic when he hit the crossbar from 25 yards in the first half.
Celtic manager Neil Lennon made three changes to the side that defeated Aberdeen on Saturday, with Virgil van Dijk making his first start since his close-season move from Eredivisie side Groningen. Mikael Lustig and James Forrest also came into the starting XI.
Viktor Kumykov made 10 changes to the Karagandy team that beat Astana 2-1 on Saturday, and was clearly keen to focus on the team's Champions League aspirations.
It was Celtic who made the brighter start, pressurising goalkeeper Alexandr Mokin at corners, although he did make an excellent point-blank save from a Georgios Samaras header.
Fraser Forster had been a bystander in the Celtic goal until Karagandy opened the scoring with 12 minutes gone.
The visitors failed to clear their lines from a Nikola Vasiljevic long throw and Finonchenko ghosted in between Joe Ledley and Emile Izaguirre to poke home from close range.
Commons came close to producing a swift response when he unleashed a fierce 25-yard effort that struck the crossbar and bounced on the line before spinning safely into the hands of Mokin.
Karagandy posed a considerable threat in the air and missed a good opportunity to double their advantage when an Aleksandar Simcevic centre was headed off target by Sergei Maliy.
And they were nearly punished on the half-hour mark when Samaras glanced a Charlie Mulgrew free-kick from the left-hand side just wide of the far post.
Celtic knew they needed to try and work harder to get a foothold in the game, and should have equalised in the 52nd minute.
Izaguirre did well to cut in from the left-hand side, but blazed well over the crossbar on his weaker right foot.
And Celtic should have been level with just under 20 minutes remaining when Forrest timed his run into the box to perfection to meet Izaguirre's curling cross, but he could only head straight at the goalkeeper.
That missed proved costly as Karagandy grabbed a second when more poor defending from Gediminas Vicius' effort led to Khizhnichenko having the simplest of headers from six yards to send the home fans into raptures.
Celtic's hopes now hang by a thread and they will look to overturn the deficit at Celtic Park on August 28.
|Coach: V. Kumykov|
|Inter 3 Bologna 2: Candreva prevents remarkable turnaround in Coppa Italia thriller|
|FA Cup Review: Non-league Lincoln stun Ipswich, Burnley and Palace through|
|Gabon v Burkina Faso: Aubameyang says hosts have learned from Guinea-Bissau setback|
|Mali 0 Egypt 0: El-Hadary makes history in stalemate|
|El-Hadary oldest AFCON player ever - 44-year-old Egypt goalkeeper makes history|
|Reus and Gotze on target but Bender injured in Dortmund win|
|Toure shunning lavish China interest to stay at City, says Seluk|
|Rahman´s AFCON in the balance, says Ghana boss Grant|
|Just 14 goals conceded and nine clean sheets - How Vertonghen blow could impact Tottenham|
|Ghana 1 Uganda 0: Andre Ayew hands Black Stars nervy victory|
|Swansea snap up Carroll and Olsson in double swoop|
|All is forgiven? - Costa trains with full Chelsea squad after reported Conte bust-up|
|I would throw myself off a bridge for Luis Enrique - Rakitic dismisses Barca rift rumours|
|Was Juventus´ new logo inspired by tennis star?|
|Smooth sailing for Liverpool in Plymouth? Klopp expects tough test|
|Demichelis re-joins Malaga until end of season|
|Cameroon v Guinea-Bissau: Broos urges new heroes to emerge|
|Boxing champ hits Carragher with Chinese Super League comeback prank|
|Zidane backs Navas and defends Benzema as Madrid aim to bounce back|
|Deportivo bring in Kakuta from Hebei after CSL rule changes|
|Matip could miss eight games without doing anything wrong - Klopp|
|United trigger Valencia´s contract extension|
|Ronaldo returns to Real Madrid´s Copa squad|
|FA fine Sagna for Instagram post|
|Nedved does not foresee more January business for Juventus|
|Rafinha injury blow for Barcelona|
|Villas-Boas fumes at CSL foreign player crackdown|
|Ibrahimovic invaluable to Manchester United youngsters - Rashford|
|Robben rejected China move|
|A-League review: Phoenix rise to the occasion to end Victory´s streak|
|Van Gaal slams English media over treatment at Manchester United|
|Mignolet: Liverpool in better position to win title than in 2013-14|
|Giroud wants Premier League title but understands China temptations|
|Tianjin forced to scrap moves for Costa, Benzema, Cavani and Falcao|
|My goal was better than Mkhitaryan´s - Giroud|
|Pochettino not interested in Argentina job|
|Kane: Tottenham can win Premier League|
|Corinthians dreaming of Drogba - Paulo Roberto|
|Coutinho calls for Liverpool focus|
|Chiellini compares Pogba to LeBron and Bolt|
|Maradona to become Napoli ambassador|
|Mihajlovic furious after Torino collapse|
|Icardi has offers from China - Wanda Nara|
|Pogba can cope with pressure - Ibrahimovic|
|´My half-time words will stay in the dressing room´ - Montella annoyed with AC Milan|
|Juventus unveil dramatic change to club logo - but not everyone´s a fan|
|´I do not think I will return to coaching´ - Van Gaal set to call it quits|
|Torino 2 AC Milan 2: Bacca caps thrilling comeback as hosts pay the penalty|
|DR Congo 1 Morocco 0: Kabananga pounces on blunder to give 10 men the points|
|´Happy and comfortable´ Sanchez dismisses Arsenal exit talk|
|How much?! West Ham flop Simone Zaza could cost Valencia €20m|
|Mali v Egypt: Salah leads Pharaohs´ bid for AFCON glory|
|Sevilla concede they ´cannot force´ sporting director Monchi to stay|
|Ivory Coast 0 Togo 0: Reigning champions held to opening draw by Adebayor and co.|
|Goalkeeping woes, Stones and tactical confusion - How Guardiola is making life difficult for himself|
|Ozil and Sanchez can be persuaded to stay - Cech|
|Pogba: I rejected Barcelona and Real Madrid|
|Ghana v Uganda: Gyan dreams of first trophy since 1982|
|Chiellini: Juventus a work in progress|
|Robben agrees Bayern renewal until 2018|
|Hazard: Goals do not matter to me|
|Bennell pleads not guilty to eight child sex offences|
|Muller fed up with debate over Bayern role|
|Wenger glad Sanchez is not ´a Costa problem´|
|Flick resigns as DFB´s sporting director|
|Gomis ´can´t wait´ to welcome Payet to Marseille|
|Chinese FA changes foreign player rules after ´irrational´ spending|
|Like father, like son: Justin Kluivert follows in dad´s footsteps|
|´No reason to lose him´ - Marotta rubbishes talk of Allegri exit|
|Courtois: We don´t need Costa|
|Kane: Tottenham players won´t go to China|
|Noble ´angry and disappointed´ with Payet|
|Klopp furious over Matip uncertainty|
|Wenger surprised by tight Premier League|
|´Money is not everything´ - Conte issues warning amid China speculation|
|Fiorentina defeat a ´bad setback´ - Allegri|
|´This will elevate this group of players´ - Sampaoli revels in Sevilla late show|