THE outcome of their penultimate Group H match last night may well have been meaningless for Celtic with qualification for the knockout rounds of the Europa League no longer a possibility.

Yet, the manner of the AC Milan defeat was still deeply concerning for manager Neil Lennon, given a stay of execution by the Parkhead board this week in the wake of a humiliating home loss to Ross County, in his current predicament.

Lennon desperately needed a vastly improved performance from his side against Milan in the San Siro to quell the growing unrest among their supporters, many of whom had protested following the Betfred Cup exit on Sunday, and justify the backing he has received from directors.

Unfortunately for him, the defensive deficiencies which had seen Celtic concede 23 goals in their previous 10 outings were still very much in evidence. Their failings at the back must be addressed if the slump in form is to be halted and the man in charge is to avoid the sack. But it is becoming increasingly difficult to see a solution.

Lennon tinkered with his both the make-up of his rearguard and his team formation once again. Christopher Jullien dropped to the bench and Nir Bitton came in at centre half. But that change and the move back to a 4-2-3-1 from a 3-5-2 make no difference. Nothing seems to be working for him at the moment.

The Glasgow club certainly started superbly. They romped into an early two goal lead thanks to Tom Rogic and Odsonne Edouard goals in the opening 14 minutes and could easily have found themselves even further in front.

However, Hakan Calhanoglu and Samu Catillejo had quickly restored parity and second-half strikes from Jens Petter Hauge and Brahim Diaz made it another depressing evening for Lennon.

Celtic were gifted a goal in the seventh minute when Rade Krunic failed to control a pass from his goalkeeper Gianlugi Donnarumma on the edge of the AC Milan area. Rogic pounced, took two touches and then placed a shot into the bottom left corner of goal.

The visitors should have built on their lead six minutes later after Jeremie Frimpong, restored to the side on the right wing, burrowed his way into the hosts area. He squared to Edouard and the striker was preparing to take a shot when Callum McGregor stepped in to try his luck instead. His attempt flew straight at Donnarumma and was easily parried. It was a wasted opportunity.

However, Lennon’s men had forged further ahead almost immediately. Ryan Christie split open the opposition defence with a delightful reverse pass and Edouard found himself with time and space. The forward showed great composure and no little skill to chip over the advancing Donnarumma and into the net.

But Celtic’s defensive woes had soon resurfaced; they squandered what should have been a comfortable advantage by letting in two goals in the space of three disastrous minutes.

Christie gave away a free-kick in a dangerous area when he scythed down Ante Rebic needlessly just outside his box. The playmaker deservedly picked up a booking from Spanish referee Ricardo de Burgos and will be suspended for the meeting with Lille in Glasgow next Thursday.

Hakan Calhanoglu stepped forward and whipped over the defensive wall and beyond Vasilis Barkas. The Celtic goalkeeper, who has reclaimed his place from Scott Bain, was well positioned to keep the attempt out. But he took a step in the other direction immediately after the winger had made contact. The £5m summer signing continues to struggle.

The Greek internationalist, though, wasn’t to blame for the equaliser in the 26th minute. Jens Petter Hauge received the ball from Calhanoglu on the left and cut it back to Rebic who was lurking just outside the six yard box. The ball broke to Samu Catillejo and neither Kristoffer Ajer or Diego Laxalt could block his effort.

It must have been soul-destroying for Lennon to witness on the touchline. When Frenck Kessie went unpunished by the match official for blatant barge on Frimpong he cracked. “Anyone could f****** see that!” he yelled. It was obvious to any onlooker the home team were in the ascendency.

Hauge, the Norwegian midfelder, gave AC Milan the lead five minutes into the second-half with a superb individual goal. He picked up possession wide on the left, cut inside Hatem Elhamed, held off Frimpong and jinked past McGregor before slotting into the bottom right corner before Nir Bitton could block him.

With 40 minutes remaining and Stefano Pioli’s side in complete control things were looking ominous for Scott Brown and his team mates. They deserve credit, though, for regrouping and coming close to levelling on more than one occasion. Christie forced an exception save from Donnarumma with a free-kick in the 73rd minute.

But AC Milan killed off any hope of Celtic salvaging a morale boosting point with eight minutes left. Hauge outmuscled Elhamed and then supplied Diaz. With Ajer posted missing the substitute had the simplest of tasks to dink over Barkas with the outside of his right foot.

The 4-2 triumph meant that Milan will join Lille, 2-1 victors against Sparta Prague in the other game, in the Europa League knockout rounds next year.

Celtic now require to defeat St Johnstone in the Premiership to ease the pressure on their beleaguered manager after losing their third consecutive game on the continent for the first time in 13 years.