Nothing can be taken for granted by Brendan Rodgers and his players after this extraordinary 90 minutes which saw them let slip a 3-0 half-time lead with the concession of two quickfire goals to Hapoel Beer-Sheva before an hour had passed.
The Scottish champions recovered with strikes from substitute Moussa Dembele and captain Scott Brown restoring a three-goal cushion which should be enough to get them over the line in Israel next Tuesday night.
Celtic produced passages of thrilling football on a thunderous night in the east end of Glasgow but also offered evidence that the defensive frailty which cost them so dearly in Europe under Ronny Deila has yet to be resolved by Rodgers.
There was a degree of surprise in his starting line-up which had no place for Dembele, the stoppage time tie-winner in the previous round against Astana. But his decision to leave out the French striker in order to accommodate Tom Rogic as an advanced attacking midfielder in support of Leigh Griffiths was dramatically vindicated when the Australian international made a ninth minute breakthrough.
It was the first Hapoel Beer-Sheva had conceded away from home in the competition, having kept clean sheets on their previous trips to Sheriff Tiraspol and Olympiacos.
Their hopes of proving similarly obdurate here melted away during a frenetic opening to the contest. Hapoel goalkeeper David Goresh, who had made a smart save to deny a Brown effort in the third minute, was forced to rush from his line as Scott Sinclair raced onto a clever through ball from Griffiths.
Goresh lost the race and clearly fouled Sinclair just outside his penalty area. Slovenian referee Damir Skomina played an excellent advantage as the ball broke back into the path of Rogic who guided a shot into the vacant net from around 22 yards.
Even before that goal, Hapoel had showed a willingness to be more enterprising in attack than their defensive reputation had suggested. It contributed to an open and intensely paced encounter which suited Celtic ideally.
Much to Rodgers’ dismay, they had a penalty appeal turned down when Sinclair went down under Loai Taha’s challenge. But he did not need to have any concerns over the likelihood of his team increasing their advantage.
Celtic carried a constant hint of menace in their attacking work as Sinclair, Rogic and James Forrest all linked effectively with Griffiths. Sinclair should have doubled the lead in the 35th minute when he was picked out by a good cross from Kieran Tierney but the former Aston Villa man struck his shot straight at Goresh who saved comfortably.
But Celtic did make it 2-0 four minutes later with a brilliantly worked and precisely finished move. It was sparked by Kolo Toure, the veteran defender surging through the centre of midfield to help put Hapoel on their heels. Sinclair picked up the momentum, feeding a pass to Forrest on the right. The winger’s dinked cross picked out Griffiths who steered a downward header beyond Goresh from around eight yards. The striker then almost knocked Rodgers off his feet as he sprinted to celebrate with his manager.
As it stood, it was already a hugely satisfying opening period for Celtic even before Griffiths seemed, to all intents and purposes, to tighten their grip on the tie in first-half stoppage time. Fouled on the right hand corner of the area by Shir Tzedek, Griffiths got up to take the free-kick himself. Displaying exceptional technique, he curled his left-foot effort over the defensive wall and beyond the hand of the helpless Goresh into the top corner.
In some senses, it mirrored the promising situation Celtic engineered for themselves at the same stage of the competition last season against Malmo. The memory of squandering a dominant position on that occasion served as a warning there was still work to be done for the champions.
That reality was underlined in startling fashion by Hapoel’s rapid double strike which put the tie firmly back in the balance. Brazilian striker Lucio Maranhao dragged the visitors back into contention with a 55th minute effort which saw him barge his way beyond some unconvincing Celtic defending and drill home a low shot which beat Craig Gordon at his near post.
Two minutes later, Hapoel’s deficit was cut to one goal as Gordon was beaten again. The Celtic keeper was powerless to keep out a sweetly struck left-foot shot from Maor Meliksen who was afforded ample space to latch onto Anthony Nwakaeme’s pass.
Rodgers responded with a swift flurry of substitutions, introducing Nir Bitton, Saidy Janko and then Dembele to the relentless fray. Just three minutes after his arrival on the pitch, Dembele provided Celtic with renewed breathing space as he made it 4-2, rising impressively to meet a Griffiths corner and thump a close range header past Goresh.
Hapoel were prevented from quickly reducing their arrears once more when Gordon produced a stunning reaction save to keep out Maharan Radi’s point blank header.
It proved to be a significant moment as Celtic then added their fifth goal with five minutes left. Goresh was punished for a poor kick-out which was pounced upon by Celtic with Brown putting the finishing touch to a swift counter attack with a firm right-foot shot.