George Tucudean then netted with the last kick of the game to seal a 5-4 aggregate win in the third qualifying round.

Neil Lennon made a big call in his team selection with summer signing Boli Bolingoli dropped and Callum McGregor moved to left-back.

McGregor had a shaky start and was beaten to a cross as Ciprian Deac headed the opener but the midfielder set up the equaliser as he and all of his team-mates improved vastly in the second half.

However, they could not manage the game when ahead and now drop down to the Europa League play-offs, where they will face AIK Stockholm or Moldovan side Sheriff with the Swedes 2-1 up ahead of their home leg.

Cluj pressed Celtic aggressively and pinned their hosts back for much of the opening stages.

McGregor had an escape as Omrani lobbed the ball to the back post. The stand-in defender lost Deac and clattered into the Cluj player after he had screwed a shot wide but the visitors' penalty appeals fell on deaf ears.

Christie began to cause problems and Mikey Johnston was not far away with a 25-yard shot at pace but Celtic fell behind in the 27th minute.

Cluj took a quick throw down the left flank and Brown could not prevent Omrani whipping in a dangerous ball to the edge of the six-yard box. Deac cut across McGregor and headed in off the far post.

The Translyvanian side smelled blood and Scott Bain made an unorthodox save with his foot from Damjan Djokovic's free-kick.

Celtic showed more urgency towards the end of the half. Christie squeezed a ball along the six-yard line and Edouard got in front of his man but stabbed well over, and Forrest made a good run into the box but shot wide from a tight angle.

Lennon stuck with his starting line-up and they responded to his half-time team-talk with their first two efforts on target inside the first couple of minutes, headers from Kristoffer Ajer and Jozo Simunovic which were blocked on the line by a defender and then goalkeeper.

The equaliser came in the 51st minute after a slick move down the left. Edouard left McGregor's low cross and Forrest beat a man and finished high into the net.

Cluj looked threatening on the break but the chances kept coming for Celtic. Edouard stabbed Christie's low cross just wide and McGregor fired over before the Frenchman swept home in the 61st minute after two defenders had got in each other's way from Hatem Abd Elhamed's cross.

Johnston, Christie and Forrest all threatened as Celtic looked for a cushion but Brown gifted the visitors a penalty in the 74th minute when he handled following a corner under no real pressure. Omrani's penalty fizzed underneath Bain's dive.

Celtic went back in front two minutes later when Edouard burst into the box and squared for Christie to net but they did not kill the game off and Omrani finished high into the net after Bain could only parry Djokovic's angled strike.

Substitute Leigh Griffiths flicked a header wide and McGregor shot off target twice as Cluj survived some intense pressure.

And Tucudean clipped the ball over Bain six minutes into stoppage-time to put his side into a play-off against Slavia Prague.